Piece of music to start to calm jazz fan with touch of anxiety (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

TO + starting letter of C [alm] + CAT (slang for a jazz enthusiast) + first letter (a touch) of A [nxiety]. A piece of music, typically for a keyboard instrument, that’s intentionally difficult (with fast-moving notes) to show off the performer’s skill.