Somehow rinsed a fish (7)
I believe the answer is:
sardine
'fish' is the definition.
(sardine is a type of fish)
'somehow rinsed a' is the wordplay.
'somehow' is an anagram indicator.
'rinsed'+'a'='rinseda'
'rinseda' with letters rearranged gives 'SARDINE'.
(Other definitions for sardine that I've seen before include "Swimmer" , "(Cramped?) fish" , "Young pilchard" , "FRENCH FISH" , "A diner's small fish" .)