Grow back (4)
I believe the answer is:
rear
This clue is a double definition.
'grow' is the first definition.
(thesaurus)
'back' is the second definition.
(something's rear is its back)
(Other definitions for rear that I've seen before include "what can be brought up, finally" , "Bring up - back end" , "Back; bring up (young)" , "The back part of something" , "Buttocks - rise up" .)