Belonging to him (3)
I believe the answer is:
his
'belonging to him' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for his that I've seen before include "That man's" , "that chap's" , "Belonging to that man" , "Belonging to the male" , "To - Coy Mistress (Marvell)" .)