Complex sentence: Beginning his career during the Big Band Era, Heller spent more than 60 years in the entertainment industry, and was noted for his association with Liberace, who he signed in 1950 and represented until the entertainer's death in 1987.
Split into simpler sentences: Beginning his career during the Big Band Era, Heller spent more than 60 years in the entertainment industry. He was best known for his association with Liberace, who he signed in 1950 and represented until the entertainer's death in 1987.