Spoil, with "on" (4)
I believe the answer is:
dote
'spoil with on' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dote that I've seen before include "Be extremely and uncritically fond of" , "Be overly fond" , "Be excessively fond" , "Lavish affection" , "Show great fondness as to Ed" .)