Complaint possibly involving setter? (9)
I believe the answer is:
distemper
'complaint' is the definition.
(distemper is a kind of health problem)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for distemper that I've seen before include "Infectious disease of animals" , "Viral infection < found in lab" , "problem for pet" , "Viral disease" , "Paint - dog disease" .)