He's clear about fish (7)

I believe the answer is:

richard

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

'fish' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see a link between them that I don't see?

'he's clear about' is the wordplay.
'he' becomes 'Ric'.
'clear about' becomes 'hard' (I am not sure about this - if you are sure you should believe this answer much more).
'ric'+'hard'='RICHARD'

Can you help me to learn more?

(Other definitions for richard that I've seen before include "Cliff --; -- Wagner" , "Mr Hannay" , "Lionheart king" , "-- Strauss, composer" , "man" .)

I've seen this clue in The Globe and Mail.

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.