Complex sentence: Hopper's endorsement brought the gallery clients from the film industry; one of them, Andrea Berens, was the fiancée of Universal Pictures' head executive John Cheever Cowdin, and arranged an audition with the studio in early 1941.
Split into simpler sentences: Hopper's endorsement brought the gallery clients from the film industry. One of them, Andrea Berens, was engaged to Universal Pictures' head executive John Cheever Cowdin, and arranged an audition with the studio in early 1941.