Her actors become musicians (9)
I believe the answer is:
orchestra
'musicians' is the definition.
(I've seen this before)
'her actors become' is the wordplay.
'become' is an anagram indicator.
'her'+'actors'='heractors'
'heractors' with letters rearranged gives 'ORCHESTRA'.
(Other definitions for orchestra that I've seen before include "Other cars (anag.)" , "Company of musicians" , "Large musical group" , "Group of musical instrumentalists" , "Group of musicians found on cart-horse" .)