Black tails of woodpecker, skua, lapwing and crow (4)
I believe the answer is:
brag
'crow' is the definition.
(synonyms)
'black tails of woodpecker skua lapwing' is the wordplay.
'black' becomes 'b' (abbreviation as in pencil classifications).
'tails of' says to take the final letters (I've seen 'tail of' mean this).
The last letters of 'woodpecker skua lapwing' are 'rag'.
'b'+'rag'='BRAG'
'and' acts as a link.
(Other definitions for brag that I've seen before include "boast; form of poker" , "Boast ? card-game" , "Talk boastfully" , "Boast, exaggerate" , "Idle talk" .)