Bird - he gets tenth part (5)
I believe the answer is:
tithe
'tenth part' is the definition.
(I've seen this in another clue)
'bird he' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'tit'+'he'='TITHE'
'gets' acts as a link.
(Other definitions for tithe that I've seen before include "Tax paid to church" , "Ancient tax" , "Levy by church, e.g." , "donation to church" , "Tax to support the church" .)