Green-blue hue (4)
I believe the answer is:
teal
I believe this is a double definition.
'green' is the first definition.
(I know that teal is a type of green)
'blue hue' is the second definition.
(I've seen this in another clue)
(Other definitions for teal that I've seen before include "Variety of duck" , "Bluish shade of green" , "Raise (subject matter)" , "Small freshwater duck and colour" , "Strange tale of a duck" .)