Returning friend’s bad make-up (4)
I believe the answer is:
slap
'bad make-up' is the definition.
(slap can mean carelessly applied make-up)
'returning friend's' is the wordplay.
'returning' says the letters should be written backwards.
'friend's' becomes 'pals' (pal is a kind of friend).
'pals' in reverse letter order is 'SLAP'.
(Other definitions for slap that I've seen before include "Strike action" , "Blow, maybe in the face" , "Right" , "Blow (in face, on back, wrist)" , "Cuff" .)