Complex sentence: He passed up a music scholarship to UCLA in order to begin his professional career in 1963, at age seventeen, backing The Everly Brothers, and went on to become one of the most sought-after recording session drummers in Los Angeles.
Split into simpler sentences: He passed up a music scholarship to UCLA in order to begin his professional career in 1963, at age seventeen, backing the Everly Brothers. He went on to become one of the most sought-after recording session drummers in Los Angeles.