Uncle's right to have birds (5)
I believe the answer is:
remus
'uncle's' is the definition.
(I've seen this before)
'right to have birds' is the wordplay.
'right' becomes 'r' (common abbreviation).
'to have' is a charade indicator (letters next to each other).
'birds' becomes 'emus' (emu is a kind of bird).
'r'+'emus'='REMUS'
(Other definitions for remus that I've seen before include "Famous twin" , "Brother of 15" , "twin brother" , "Uncle character in US folk stories" , "murdered brother?" .)