Bad character or chicken-hearted flier (5)

I believe the answer is:
crook
'bad character' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'chicken-hearted flier' is the wordplay.
'hearted' means to look at the middle letters.
'flier' becomes 'rook' (rook is a kind of birdanimal).
The central letter of 'chicken' is 'c'.
'c'+'rook'='CROOK'
'or' acts as a link.
Can you help me to learn more?
(Other definitions for crook that I've seen before include "Fence, perhaps" , "Hooked staff" , "Bend; criminal; staff" , "Professional criminal" , "Shepherd's staff" .)
