Stoker holding tail of coarse fish (5)
I believe the answer is:
bream
'fish' is the definition.
(type of fish)
'stoker holding tail of coarse' is the wordplay.
'stoker' becomes 'bram' (I've seen this in another clue).
'holding' means one lot of letters goes inside another.
'tail of' says to take the final letters.
The last letter of 'coarse' is 'e'.
'bram' enclosing 'e' is 'BREAM'.
(Other definitions for bream that I've seen before include "Swimmer" , "Fish of the carp family" , "Edible fish" , "Bar me from the freshwater fish" , "River fish" .)