Does he appear in a musical? (6)
I believe the answer is:
cheats
'does' is the definition.
(do can mean to cheat or defraud)
'he appear in a musical?' is the wordplay.
'appear in' indicates putting letters inside.
'a musical?' becomes 'Cats' (Andrew Lloyd Webber musical).
'he' placed into 'cats' is 'CHEATS'.
(Other definitions for cheats that I've seen before include "Doesn't follow the rules of the game" , "Swindles or deceives as at cards" , "Swindles in chaste manner" , "Deceivers" , "Acts dishonestly, perhaps in card game" .)