Reeks from mackerels in chowder (4)

I believe the answer is:

clam

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

'chowder' is the definition.
(clam chowder is a kind of chowder)

I can't explain the remainder of the clue.

(Other definitions for clam that I've seen before include "Mollusc, one proverbially reticent" , "ringing noise produced by > very reticent type" , "Large shellfish with hinged shell" , "Quahog" , "What could grip" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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.