A good doctor has fish; confusing! (7)

I believe the answer is:

addling

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

'confusing' is the definition.
(addling is a kind of confusing)

'a good doctor has fish' is the wordplay.
'good doctor' becomes 'dd' (Doctor of Divinity. I am not sure about the 'good' bit.).
'has' is a charade indicator (letters next to each other).
'fish' becomes 'ling' (ling is a kind of fish).
'a'+'dd'+'ling'='ADDLING'

Can you help me to learn more?

(Other definitions for addling that I've seen before include "Becoming rotten" , "Taking order from" .)

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

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