Has made a mess of fine cod, they disclose (7)

I believe the answer is:

confide

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

'disclose' is the definition.
(confiding is a kind of disclosing)

'has made a mess of fine cod they' is the wordplay.
'fine cod' anagrams to 'CONFIDE'.
But, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for confide that I've seen before include "Tell secret as to friend - mum's the word" , "Impart secrets to someone" , "Tell secret or entrust to" , "Trust wholly (in person)" .)

I've seen this clue in The Irish Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.