Shade cowardly (6)
I believe the answer is:
yellow
This clue is a double definition.
'shade' is the first definition.
(I know that yellow is a type of shade)
'cowardly' is the second definition.
(yellow can informally mean cowardly)
(Other definitions for yellow that I've seen before include "Fearful - colour" , "Kipling's Dog Dingo" , "Telephone reference book" , "Small European bunting" , "like a canary" .)