Fish left in sink (8)
I believe the answer is:
flounder
'fish' is the definition.
(I know that flounder is a type of fish)
'left in sink' is the wordplay.
I cannot really see how this works, but
'left' could be 'l' (common abbreviation) and 'l' is found within the answer.
'sink' could be 'founder' (foundering is a kind of sinking) and 'founder' is found within the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for flounder that I've seen before include "Small flatfish" , "A fish; be out of depth" , "Have difficulties with the flatfish" , "Stagger clumsily in mud (or water)" , "Have difficulty" .)