Muscular companion of Nemo is perfectly fine (5-4)

I believe the answer is:

hunky-dory

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'fine' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for hunky-dory that I've seen before include "In excellent condition" , "Excellent - fine" , "A-OK" .)

I've seen this clue in The Times.

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