Could Carl Reiner be apoligizing for the feebleness of his new comedy, "The One and Only," by inserting a brief excerpt from "Your Show of Shows"? The effect is certainly more devastating than any criticism from an outsider could be.

While it's been a constant ordeal watching the star of "The One and Only," Henry Winkler, pretend to be an irrepressible, irresistible clown, you don't fully appreciate how misguided and pathetic his strenuous efforts are until Sid Caesar suddenly reappears in his prime to demonstrate genuine comic prowess in a flash. If only there were some way of subsituting that kinescope for the rest of the movie!

Opening today at area theaters, "The One and Only" is the outmoded branichild of Steve Gordon, the former "creative director" at Young and Rubicam. The premise behind his script, a chronicle of the ludicrous show business career of an aspiring entertainer called Andy Schmidt, couldn't be more dunious, but, I wouldn't be surprised to see it mistaken for "heart" by a mass audience.

Although Andy acts obnoxious from the beginning, when we're introduced to him as a hideously show-bizzy brat in the late '30s, insulting his parents' friends while preparing to show off his Al Jolson impression, the film-makers expect the audience to accept the sentimental illusion that there's a really wonderful guy and rare talent underneath. The evidence of the story itself contradicts this illusion. The brash little creep appears to grow up into a somewhat older, less-forgivable brash little creep. At the same time, he seems to decline in raw talent.

Nevertheless, audiences will be obliged to play along with the gag if they hope to enjoy themselves, and very few paying customers enter a theater seeking emotional alienation. Winkler's presence its supposed to guarantee advance approval. Andy's repellent character traits will be forgiven because everyone knows that's only Fonzie putting on an act. Winkler doesn't bring out aspects of Andy that might make his brashness interesting and credibly appealing. As an actor, he fails at an assignment that a Richard Dreyfuss night have aced, even working from the handicap of a Steve Gordon script.

Wrinkler and Kim Darby embody a romantic mismatch that suggests a low-budget version of the Robert De Niro-Liza Minnelli relationship in "New York, New York."

They met "cute" at something called Ohio Southern University in the late '40s, when Andy has matured into the campus cut-up and puts the rush on Darby's Mary, a passive, conventional middle-class girl.

His apparent need to dominate her sort of girl might have proved an intriguing motive in a more sophisticated comedy. In this oblivious context it's a loose end tied off by sentimentality. Andy may behave like an incorrigible jerk, but that's okay with Mary, who gravely expresses the screenwriter's sentiments: "You're so very sad and very funny, which I happen to love."

Winkler is certainly at his saddest when striving to appear funny, especially physically funny. Although his antics suggest a Jerry Lewis who didn't make it, a Jerry Lewis without comis spontaneity and rhythm, Winkler seems to favor Jack Benny's facial expressions. One keeps counting off the sources - there's even a borrowing from Chaplin in "City Lights" - without responding to a pleasurable new synthesis.

Winkler had one genuinely funny bit: upon meeting the heroine's father, played by William Daniels, he hugs him calls him "Dad." The hitch is that anybody could probably do it just as well, given a foil as prissy as William Daniels. Gene Saks gets most of the punch lines as a wrestling promoter who seems to prefigure Don Rickles. The level of the wit may be accurately gauged by noting that about every other wisecrack out of this wiseacre's mouth is a disparaging remark about his "faygeleh" son.

The movie is so full of dead air and missed beats that to be charitable I supposed one should credit Reiner with anticipating gales of laughter to cover his lack of style. It will be depressingly ironic if a large public does elect to cover for him. Reiner might degenerate into a terminal soft-soaper if "The One and Only" duplicates the success of "Oh, God," which could almost pass for snappy in a stylistic comparison test with his new one.

Comedians as square and strained as "The One and Only" deserve to lay an egg, but they frequently luck out. Still, if I were Henry Winkler, I wouldn't quit "Happy Days" just yet.