Complex sentence: Mitchell performed and recorded with the Kenny Clarke-Francy Boland Big Band, in Europe, in the late 1960s/early 1970s, and also served as musical director to Stevie Wonder for a short time during this period.
Split into simpler sentences: Mitchell performed and recorded with the Kenny Clarke/Francy Boland Big Band in Europe in the late 1960s and early 1970s. He was musical director for Stevie Wonder for a short time during this period.