Incandesce (4)
I believe the answer is:
glow
'incandesce' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for glow that I've seen before include "warmth of feeling" , "Radiate or redden" , "Shine steadily and brightly" , "Shine with heat" , "Steady radiance" .)