Black chicken decapitated (5)
I believe the answer is:
raven
'black' is the definition.
(thesaurus)
'chicken decapitated' is the wordplay.
'chicken' becomes 'craven' (I've seen this before).
'decapitated' means to remove the first letter.
'craven' with its initial letter removed is 'RAVEN'.
(Other definitions for raven that I've seen before include "Jet-black" , "Large bird of the crow family" , "Large black bird" , "Tower of London bird" , "Voraciously eat" .)