Spending "A Day With Conrad Green" would be more of a privilege if the sun set on it with greater dispatch. An afternoon with Conrad Green might have sufficed. But the Israel Horovitz adaptation of a Ring Lardner story, on public TV tonight, does have a wry, jaunty tone and sassy sense of flapper Americana. These count for something.

The one-hour taped comedy -- produced by the Maryland Center for Public Broadcasting and airing at 9 on Channel 26 and other PBS stations -- suffers from slow pacing, conflicting acting styles and a sepulchral hush where there ought to be bubbliness and zip. Norman Gevanthor, who directed the cameras, both took too polite and genteel an approach.

Fred Gwynne plays the aging Green who on the day in question is recovering from the death of his longtime right arm, Herman Plant, a social slight in the morning's newspaper and escalating complications regarding some Philadelphia jewelry and a certain attractive young lady to whom promises were made, as such promises usually are, in haste. There is also the matter of a pesky, telltale fly that manges to buzz by at particularly pivotal junctures.

Gwynne has a vast and very amusing face, and in this role he brings to mind the odd combination of Jason Robards and Elliott Gould. Most of his performance is accomplished from the neck up, and Gwynne remains consistently interesting. Just as effective as his $5 expressions and reactions, and considerably more subtle, is a fine moment when he tells a young writer who's just outlines some socko material for him, "I don't like it. It's no good."

Even the mightly Green, master of his own empire, must pay for his slights and peccadilloes. The world tumbles down, but too slowly.If only Horovitz and the directors didn't have to hew to the essentially arbitrary one-hour time frame. At 45 minutes, Green's affairs could have been wrapped up with much more energy and flair -- with a screwball comedy, "Twentieth-Century" kind of rush -- and the remaining 15 minutes occupied with, oh, a few words about Lardner, or views of the ocean, or a couple old Gerald McBoing-Boing cartoons. It doesn't much matter.