Stage performer unfortunately quits in revolt (13)
I believe the answer is:
ventriloquist
'stage performer' is the definition.
'unfortunately quits in revolt' is the wordplay.
'unfortunately' is an anagram indicator.
'quits'+'in'+'revolt'='quitsinrevolt'
'quitsinrevolt' with letters rearranged gives 'VENTRILOQUIST'.
(Other definitions for ventriloquist that I've seen before include "Voice-thrower" , "Performer with dummy" , "Dummy operator" .)