Aries came back to spoil (3)
I believe the answer is:
mar
'spoil' is the definition.
(I know that spoil can be written as mar)
'aries came back' is the wordplay.
'aries' becomes 'ram' (I've seen this in another clue).
'came back' is a reversal indicator.
'ram' back-to-front is 'MAR'.
'to' acts as a link.
(Other definitions for mar that I've seen before include "Damage; month (abbr.)" , "Spoil stuff" , "Make imperfect" , "Spanish main?" , "Blemish" .)