Complain to a creature (6)
I believe the answer is:
grouse
This clue is a double definition.
'complain' is the first definition.
(grousing is a kind of complaining)
'a creature' is the second definition.
(grouse is a kind of creature)
'to' is the link.
(Other definitions for grouse that I've seen before include "excellent in New Zealand" , "Complain like game bird" , "Grumble like game-bird" , "The complaint of a gamebird" , "Game bird - beef" .)