Circle of light around the sun during an eclipse (6)
I believe the answer is:
corona
'circle of light around the sun during an eclipse' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for corona that I've seen before include "A glow of light around something" , "Sun's envelope; cigar" , "Ring around the sun" , "Long cigar" , "Glow around conductor" .)