Deserve, you say, to get the bird (4)
I believe the answer is:
erne
'the bird' is the definition.
(erne is a type of bird)
'deserve you say' is the wordplay.
'deserve' becomes 'earn' (I've seen this in another clue).
'you say' indicates a 'sounds like' (homophone) clue.
'earn' sounds like 'ERNE'.
'to get' is the link.
(Other definitions for erne that I've seen before include "Irish lough" , "River and lake of the North" , "one that catches fish?" , "Lough of the North" , "Seabird" .)