Patron doesn't reveal musical piece (5)
I believe the answer is:
rondo
'musical piece' is the definition.
(type of musical piece)
'patron doesn't reveal' is the wordplay.
'reveal' says the answer is hidden in the clue.
'RONDO' can be found hidden inside 'patron doesnt'.
(Other definitions for rondo that I've seen before include "Musical form with returning theme" , "has repetitive theme" , "Repetitive musical form" , "Musical form with repeated theme" , "noted work" .)