In a pinch, the Washington establishment could hold a conclave on Allie Ritzenberg's tennis courts. Walter Mondale, Michael Blumenthal, Brock Adams, Cyrus Vance and Joe Califano, among others, play tennis under the watchful eye of Ritzenberg, the lean, easy-going pro at the St. Albans courts.

It was Ritzenberg, a hotshot tennis player at the University of Maryland in the Thirties, who helped make the sport chic in Washington. When First Lady Jacqueline Kennedy began taking lessons from him, Ritzenberg's reputation was made. And with domain over ten courts placed right on the edge of Cleveland Park, he's in the right place at the right time with the right game.

But at age 59, Ritzenberg is cutting his private lessons back to four-and-a-half days each week; now he takes off weekends. And his interest in tennis embraces art and antiques associated with the game. In his Glen Echo home with a panoramic view of the Potomac, Ritzenberg has dozens of Currier & Ives prints, Thomas Nast drawings, ceramics from England, hand-tinted postcards from Germany and other memorabilia honoring the game.

"As you play tennis, your see a vast number of other fields that can be approached through the game," says Ritzenberg. "Counseling, art, diplomacy, geometry and mathematics, the medical world . . . which is the fun - you're not strictly teaching. I do a lot of babysitting kind of teaching. You know, after fifteen years of teaching someone, they come in as if they were going to a psychiatrist."

Ritzenberg charges $35 for an hour's private lesson.

"I tell someone whose husband charges me $75 an hour in legal fees all he has to be is bright," he says. "I'm expected to be bright, cheery, charming, witty and talented."

Ritzenberg says this with no sarcasm. He enjoys the publishers, politicans and other pooh-bahs who are members at St. Albans. He's no tennis bum: a long-time D.C. area resident with a master's degree in sociology, he's not blind to politics. In the past, reporters have called him in search of stories. Ritzenberg, for example, knew something was up one morning when then-Secretary of Defense Robert McNamara missed his 7 a.m. lesson; what was up was the Cuban missile crisis. But Ritzenberg keeps his confidences and tries to limit the number of photographers who find it convenient to shoot informal pictures of famous faces on his courts.

Ritzenberg's New Frontier, Greater Society and (now) Carter cabinet connections lend a cachet to St. Albans that means prospective members may have to wait as long as a decade to join. Ritzenberg admits that exceptions are sometimes made, which is one reason he tries to avoid cocktail parties - invariably he is asked how to inch up on the waiting list.

"I'm happy to see 35,000,000 people playing tennis, but just as popularity does to anything, it's become exploited," complains Ritzenberg. "Every real estate man thinks there's a buck to be made, the conglomerates have moved in." What used to be an intimate, friendly enterprise, Ritzenberg says, is now an impersonal, bottom-line business.

For his part, Ritzenberg sports bulky sweaters in the spring with shabby Tretorns for tennis shoes. He disdains easy status as much as the over-commercialization of tennis: "I can't stand having the name of a car dealer advertised on my car, so I don't want to see Oleg Cassini's name on my shirt."