Chicken like a canary (6)
I believe the answer is:
yellow
This clue is a double definition.
'chicken' is the first definition.
(as in cowardly)
'like a canary' is the second definition.
(I've seen this before)
(Other definitions for yellow that I've seen before include "Colour of cowardice, custard" , "Colour between orange and green in the spectrum" , "Chicken" , "This card is shown by soccer referee as a caution" , "Chicken-hearted" .)