Young setter, maybe, changing nothing by going back? (3)
I believe the answer is:
pup
'young setter maybe' is the definition.
(setter is a type of dog)
I don't understand how the rest of the clue works.
(Other definitions for pup that I've seen before include "Young seal" , "Canine young" , "Young of various animals" , "Whelp" , "Youngster" .)