Belonging to you and me (3)
I believe the answer is:
our
'belonging to you and me' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for our that I've seen before include "Belonging to us" , "Yours and mine" , "''Now is the winter of ... discontent'' (Richard III)" , "'-- House' (Madness song)" , "Possessed by us" .)