Good yarn about ... about fishing (9)

I believe the answer is:

piscatory

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

'fishing' is the definition.
(thesaurus)

'good yarn about' is the wordplay.
I cannot quite see how this works, but
'good' could be 'pi' (old-fashioned term for pious) and 'pi' is located in the answer.
'about' could be 'ca' (short for circa) and 'ca' is found within the answer.
'yarn' could be 'story' (synonyms) and 'story' is found within the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...

'about' acts as a link.

Can you help me to learn more?

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

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