Two gulls and another bird (9)
I believe the answer is:
sapsucker
'bird' is the definition.
(sapsucker is a kind of bird)
'two gulls' is the wordplay.
'two gulls' can mean two substitutions for 'gull'.
'gull' becomes 'sap' (I've seen this in another clue).
'gull' becomes 'sucker' (synonyms).
'sap'+'sucker'='SAPSUCKER'
'and another' is the link.
(Other definitions for sapsucker that I've seen before include "Dupes" , "bird" , "Flyer" , "woodpecker" .)