Breed of gun dog (3,6)
(Other definitions for red setter that I've seen before include "supplier of crosswords to the Daily Worker?" , "One of my best friends" , "Breed of dog" , "Shepherds are delighted to see this" , "Pet" .)
'breed of gun dog' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cocker spaniel that I've seen before include "Ponies crackle (anag) - dog" , "Mutt" , "Breed of small dog" , "Breed of gun dog" , "Small dog used in game shooting" .)