Get the girl in to identify the bird (6)
I believe the answer is:
gannet
'the bird' is the definition.
(gannet is a kind of bird)
'get the girl in' is the wordplay.
'the girl' becomes 'ann' (woman's name).
'in' means one lot of letters goes inside another.
'get' placed around 'ann' is 'GANNET'.
'to identify' is the link.
(Other definitions for gannet that I've seen before include "Gluttonous type" , "Large fish-eating bird" , "Marine bird - greedy person" , "Large seabird noted for its plunging dives for fish" , "Seabird - glutton" .)