Smeltery refuse (5)
I believe the answer is:
dross
'smeltery refuse' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dross that I've seen before include "Worthless stuff" , "It's Poor" , "Lees" , "Waste matter, refuse" , "Rubbish, scum" .)