Complex sentence: Tracy McCleary (died 2003) was a prominent part of the Baltimore jazz scene, based around his position as leader of the Royal Men of Rhythm, the house band at the Royal Theater, the premier African American music venue in Baltimore at that time.
Split into simpler sentences: Tracy McCleary (died 2003), was the leader of the Royal Men of Rhythm and a prominent part of the Baltimore jazz scene. The Royal Men of Rhythm was the house band at the Royal Theater, the premier African American music venue in Baltimore at that time.