A dog for Frederik? (5,4)

I believe the answer is:

great dane

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'a dog' is the definition.
(I know that Great Dane is a type of dog)

I can't explain the remainder of the clue.

(Other definitions for great dane that I've seen before include "Pet" , "Hamlet possibly" , "Could be barking" , "Andersen" , "Dog -- a tad green (anag)" .)

I've seen this clue in the Sydney Morning Herald.

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