Firmer with the dog (6)

I believe the answer is:

setter

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'the dog' is the definition.
(setter is a type of dog)

I cannot understand how the rest of the clue works.

(Other definitions for setter that I've seen before include "Dog trained to scent game" , "Bird trained to scent game" , "Street (anag.)" , "Dog trained to point at game" , "Crossword creator" .)

I've seen this clue in the Evening Standard.

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