Fine muscular fish (5-4)

I believe the answer is:

hunky-dory

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'fine' is the definition.
(I know that fine can be written as hunky-dory)

'muscular fish' is the wordplay.
'muscular' becomes 'hunky' (I can't justify this - if you can you should believe this answer much more).
'fish' becomes 'dory' (dory is a kind of fish).
'hunky'+'dory'='HUNKY-DORY'

Can you help me to learn more?

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

I've seen this clue in The Times.

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