Chicken decapitated crow (5)
I believe the answer is:
raven
'crow' is the definition.
(I have seen 'Large crow' mean 'raven' so perhaps 'crow' could also mean 'raven')
'chicken decapitated' is the wordplay.
'chicken' becomes 'craven' (I've seen this before).
'decapitated' means to remove the first letter.
'craven' with its first letter removed is 'RAVEN'.
(Other definitions for raven that I've seen before include "pig" , "Poe's poetic bird" , "Bird of ill omen" , "Large black bird" , "Flighty type" .)