The coal miner's dog? (6)

I believe the answer is:

collie

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'dog?' is the definition.
(collie is a kind of dog)

I cannot understand how the remainder of the clue works.

(Other definitions for collie that I've seen before include "Sheep-herding dog" , "See 2" , "Sheepdog with long pointed muzzle" , "Popular kind of sheepdog" , "Popular sheepdog like Lassie" .)

I've seen this clue in the Evening Standard.

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