Glowing coals (6)
I believe the answer is:
embers
'glowing coals' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for embers that I've seen before include "Remains of coal fire" , "Hot fragments of wood or coal" , "Live coals" , "Glowing coals" , "Pieces in a dying fire" .)