Complex sentence: Over the course of his career, Stiefel has worked with Bette Midler, Prince, and Toni Braxton, amongst others, but is best known for his association with Rod Stewart, whom he has managed since 1983.
Split into simpler sentences: Over the course of his career, Stiefel has worked with Bette Midler, Prince, and Toni Braxton, amongst others. He is best known for his association with Rod Stewart, whom he has managed since 1983.