Not the setter, but the setter free! (8)
I believe the answer is:
springer
'free' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for springer that I've seen before include "hound" , "Kind of spaniel" , "Breed of spaniel" , "A spaniel; stone in arch" , "A bounder" .)