Bird like a chicken drops head (5)
I believe the answer is:
raven
'bird' is the definition.
(raven is a kind of bird)
'a chicken drops head' is the wordplay.
'a chicken' becomes 'craven' (both can mean cowardly).
'drops head' means to remove the first letter (I've seen 'dropping head' mean this).
'craven' with its initial letter taken off is 'RAVEN'.
'like' acts as a link.
(Other definitions for raven that I've seen before include "Poe's poetic bird" , "Jet-black" , "Flyer" , "Tower of London bird" , "Type of crow" .)