One eats fish that's spicier for Cockney (5)
I believe the answer is:
otter
'one eats fish' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for otter that I've seen before include "Fish eater of the weasel family" , "Mammal, 'Tarka'" , "Mine is made safe by this" , "Lithe swimmer" , "Aquatic beast" .)