Glowing cinder (5)
I believe the answer is:
ember
'glowing cinder' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ember that I've seen before include "Smouldering piece of dying fire" , "showing residual fire" , "Remnant of bonfire" , "Glowing remainder of a fire" , "what causes a warm glow" .)