A bad actor returning to be servant (4)
I believe the answer is:
amah
'be servant' is the definition.
(Asian term for a maid)
'a bad actor returning' is the wordplay.
'bad actor' becomes 'ham' (a ham is someone who overacts).
'returning' is a reversal indicator.
'ham' back-to-front is 'mah'.
'a'+'mah'='AMAH'
'to' is the link.
(Other definitions for amah that I've seen before include "Maid serving" , "Children's nurse" , "nurse from abroad" , "Chinese nursemaid" , "Old Asian maid" .)