Fish stank (5)
I believe the answer is:
smelt
This clue is a double definition.
'fish' is the first definition.
(smelt is a kind of fish)
'stank' is the second definition.
(I've seen this before)
(Other definitions for smelt that I've seen before include "sensed as fishy?" , "Savoured" , "were high" , "emitted noxious effluvium" , "Got a whiff of" .)