Open Monday through Friday, noon to 2:30 p.m.; Monday through Saturday, 5:30 to 11 p.m. All major credit cards. Reservations.

Prices: Dinners including main course, salad, dessert and coffee average $9.50 to $10.50.

Le Duck, starting with its name, is a compromise. Trying to make the transition from Le Pescadou to a reincarnation of Le Canard, it flounders. It wavers between fish and fowl, becoming instead a hybird.

The wine list is the most obvious example of Le Duck's problem. If a restaurant is specializing in duck, why are most of the wine white? Left over from Le Pescadou, one assumes. Whatever the reason, the half-dozen red wines provide a narrow choice, none of them attractive buys. The solution might be to settle for a spicy white like the Hugel Gewurztraminer, but at $12 for a '77, it, too, is a compromise. Throw up your hands and order a carafe, and you will find it served in a fish-shaped bottle.

So you accept the fact that there is something fishy at Le Duck. The rest rooms are identified by life preservers. The dining rooms are divided by a fish tank. And five of the seven special entrees plus all the special appetizers are seafood. Clearly, the restaurant is not called Le Duck because it is exclusely a duck restaurant.

Thus, one would assume, it is a restaurant that prepares duck very well. But that, too, turns out to be an unfair assumption. Le Duck, at first glance, seems to prepare duck about 10 different ways. What it really does is prepare duck one way-not an especially good way-and serves it with 10 different finishing touches. The duck is presumably roasted and halved, but it tastes as if it were steamed until tender and defatted, then crisped in the oven. The result is soft, its layer of fat rendered, the meat stringy and smacking of reheating. The skin is indeed crisp, but that is the main appeal of the dish.

One does have the choice, however, of duck with cherries or oranges, with peas or armagnac and green peppercorns, sometimes with turnips or sauerkraut. But duck with trunips, rather than being cooked together so they can exchanged their falvors, is the product of a shotgun wedding: thick brown gravy linking boiled turnips ith duck, there being no other communication between them. Duck with green peppercorns sports a similar gravy, this time with a few peppercorns floating in it, but no distinguishing flavor. Duck with cherries or peaches or oranges is distinctly different, though far from a distinctive dish. A one-dimensional sweet sauce instead of brown gravy is poured over the bird.

For variety, a half dozen chicken dishes are offered. The chicken, however, tastes no perkier than the duck. Le poulet a l'estragon gasped for breath under enough tarragon to suffocate, in a sauce floating lumps of starch.

Le Duck, however, has its saving graces. The kitchen carves carrots and turnips with admirable attention to detail, to the benefit of one day's special, aioli garni. In this dish, somewhat fresh codfish is surrounded by these pretty carvings, the sauceboat of garlic mayonnaise enough of an excuse for eating the dish. Canard paysanne may be the best of the duck dishes, for it has the benefit of fresh carrots and mushrooms and diced bacon to season it.

Thus, vegetables play a small role but sometimes save the meal. Even the potatoes served with the chicken are a well browned suaute, far more appetizing than the gravy-soaked white rice under the duck.

Starting a meal with moules farcies-slightly sandy, but handsomely seasoned with tomato, bacon, oregano and garlic -or fresh and buttery clams casino gets things off on the right foot. Fish soup tastes like crab boil cooked in tomato broth.

The restaurant makes some generaous gestures; a garlicky, scallion-sharp cream cheese spread accompanies the bread, though far better bread can be bought in Washington. Main courses-most of them $9.50 to $10.50-include a salad of good mixed greens well incorporated with a creamy vinaigrette that is heavy-handed but close to being good. And in the same price is included dessert.

Dessert is a struggle. Forget the tarts and the mousse. Don't bother with the brie. If you ask for a piece of the fresh fruit that is displayed on the dessert table, you will be refused, for it is only a decoration. Twist the waiter's arm to bring you a parfait. It is chock full of chocolate chips and strawberries buried in chocolate ice cream, and drenched with enough liqueur to soften the edges of the meal.

Le Duck is a pretty place, a comfort of rough beams and stucco and old brick. The lighting is soft. On the tables are flowers in low vases, and propane candles in red globes. Its dining room staff is handsomely turned out, and can be quiteadept though sometimes abrupt. Given the tastefulness of its dining room, Le Duck is not expensive by Washington's French restaurant standards.

It is easiest to characterize Le Duck by what it is not. It is not quite a duck restaurant. It is not quite a fish restaurant. It is not quite a turkey.