Yellowbelly (6)
I believe the answer is:
coward
'yellowbelly' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for coward that I've seen before include "Yellow type" , "Yellow-belly" , "Author of 'Blithe Spirit'" , "Faint-hearted person" , "One chicken-hearted" .)