Wader changes colour (9)
I believe the answer is:
turnstone
'wader' is the definition.
(type of wading bird)
'changes colour' is the wordplay.
I cannot really see how this works, but
'changes' could be 'turns' (turning is a kind of changing) and 'turns' is found within the answer.
'colour' could be 'tone' (toning is a kind of colouring) and 'tone' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for turnstone that I've seen before include "Relative of sandpiper, named for how it seeks food" , "Small short-billed sandpiper" , "Shore bird" , "Wader" , "Flier" .)