Catch, yet head off fish (7)

I believe the answer is:

latchet

I'm a little stuck... Click here to teach me more about this clue!

'fish' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I don't see?

'catch yet head off' is the wordplay.
'catch' becomes 'latch' (latch is a kind of catch).
'head off' means to remove the first letter.
'yet' with its first letter taken off is 'et'.
'latch'+'et'='LATCHET'

Can you help me to learn more?

(Another definition for latchet that I've seen is " Old thong".)

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

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