belonging to me (4)
I believe the answer is:
mine
'belonging to me' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for mine that I've seen before include "Tunnel for extraction of coal etc" , "An abundant source, as of gold" , "Excavation in the earth for digging coal etc" , "Pit; source" , "Pit; belonging to me" .)