One cleans fish (4)
I believe the answer is:
char
I believe this is a double definition.
'one cleans' is the first definition.
(I've seen this before)
'fish' is the second definition.
(char is a kind of fish)
(Other definitions for char that I've seen before include "Scorch - fish - cleaning lady" , "Drink" , "Kind of small trout - burn it black" , "Make black by burning, or a small trout" , "House cleaner" .)