Glowing circle (4)
I believe the answer is:
halo
'glowing circle' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for halo that I've seen before include "Holy ring" , "Sign of holiness" , "Saintly ring" , "Ring of light round head" , "Luminous sign of saintliness" .)