A shade cowardly (6)
I believe the answer is:
yellow
This clue is a double definition.
'a shade' is the first definition.
(I have seen 'Custardy shade' mean 'yellow' so perhaps 'shade' could also mean 'yellow')
'cowardly' is the second definition.
(similar in meaning)
(Other definitions for yellow that I've seen before include "Jaundiced - yolk" , "Lemon shade" , "Pusillanimous" , "'Caution' colour" , "Colour between orange and green in the spectrum" .)