She does burn fish (4)
I believe the answer is:
char
I believe this clue is a triple definition!
'she does' is the first definition.
(a charwoman, domestic worker)
'burn' is the second definition.
(charring is a kind of burning)
'fish' is the third definition.
(char is a kind of fish)
(Other definitions for char that I've seen before include "'Mrs Mopp'" , "Singe, scorch" , "Scorch - fish - cleaning lady" , "Brown" , "Make black by burning, say toast" .)