It Happened in New York

Vania Nardi, a temperamental movie star appearing in New York City, is fed up with publicity stunts and hires Charley Barnes, a taxicab driver, as her bodyguard. He manager, Greg Haywood, hires a phony Prince to escort Vania to the premiere of her new film, but Vania takes Charley instead. Chris Edwards, Charley's fiancée, goes with the Prince. This does not set well with Charley and he and the Prince are soon engaged in a lively fist-fight in the theatre. - IMDb