The term romantic comedy-thriller stirs many affable memories and, when it is attached to a new film, a few fond hopes. Think of Robert Donat, suave fugitive of The 39 Steps, double-talking his way out of a political rally and into the clutches of the man with the missing fingertip. Or Cary Grant doing anything in almost any Hitchcock caper: wooing Grace Kelly in To Catch a Thief, dodging a malefic crop duster in North by Northwest. Grant also adorned the genre's apogee, Stanley Donen's Charade, in which the star has five identities and a protective lust for Audrey Hepburn. Neat plotting, chic dialogue, a funny-grotesque supporting cast and enough frissons to send an audience out spooked and happy. They don't make pictures like these anymore. Case in point: Legal Eagles. It ought to work. Robert Redford can give good suave; Debra Winger could be Audrey Hepburn (or Kate) brought down to earth. The plot ransacks honorable sources: bantering, romancing lawyers from Adam's Rib, silky threats at an art auction from North by Northwest, the murderer and his motive from Charade. The movie's Manhattan locations exploit some of the most glamorous spots in Greenwich Village and Tribeca. Wallpapering the film is the work of 37 modern artists, which was flown at great expense from New York City to Universal's California studios. A budget of $30 million and change ought to be enough to get this down right. Isn't, though, because somebody forgot to hire a story editor. The incidents in a comedy-thriller can be implausible but never absurd, and Legal Eagles is pocked with absurdities. Trapped in a warehouse about to be blown to shards, klutzy Assistant D.A. Tom Logan (Redford) and plucky Lawyer Laura Kelly (Winger) find a forklift tractor (and the keys), jump on, start it and crash through a metal door, all in five seconds. Logan, who has made tabloid headlines by being caught in bed with a spacey artist (Daryl Hannah) the night she is supposed to have killed her ex-lover, is allowed to act as one of her attorneys at the murder trial. Finally, the real murderer forces Kelly and the artist to bang noisily on a sculpture while dozens of guests attend a stately memorial service in an adjacent room. Ivan Reitman is the coarsest and canniest of directors; Meatballs, Stripes and Ghostbusters had no subtlety or style, but all profitably exploited Bill Murray's goofy hipness. Here, however, Reitman misreads the audience's pulse. The villain of Legal Eagles is a pathological firebug, and Reitman tries to play it like Arson and Old Lace. (He punctuates this theme with a performance- art piece by Hannah so bizarre it could empty movie houses quicker than a bomb threat.) Which leaves the top two stars to their own considerable resources of charm and mother wit. Redford looks terrific, and has honed his stutter-step diction into a cagey character trait. Winger, unflatteringly photographed, is still the most ingratiating of Oscar-worthy actresses. Neither deserves to be laden with this leaden souffle. Verdict on Legal Eagles: guilty of genre sabotage. Cast dismissed.