Soap actor sorry to return to box (7)
I believe the answer is:
shampoo
'soap' is the definition.
(I have seen 'Liquid soap' mean 'shampoo' so perhaps 'soap' could also mean 'shampoo')
'actor sorry to return to box' is the wordplay.
'actor' becomes 'ham' (ham is a kind of actor).
'sorry' becomes 'oops' (I've seen this before).
'to return' is a reversal indicator.
'to box' is an insertion indicator ('box' can mean contain, as in to put in a box).
'oops' backwards is 'spoo'.
'ham' put within 'spoo' is 'SHAMPOO'.
(Other definitions for shampoo that I've seen before include "Ooh, spam! (anag.)" , "Cleansing agent" , "16 21 [INDIAN IMPORT]" , "Hair wash preparation" , "Soap for washing hair" .)