Angelic topper (4)
I believe the answer is:
halo
'angelic topper' 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 "Corona" , "Saint's overhead ring of light" , "Angel's head-light" , "Glowing ring (around saint's head)" , "Holy ring" .)