Luminous (7)
I believe the answer is:
lambent
'luminous' is the definition.
(I know that luminous can be written as lambent)
This is the entire clue.
(Other definitions for lambent that I've seen before include "Glowing with a soft radiance" , "shedding some light" , "Shining example" , "Gleaming with a soft radiance, the moon perhaps" , "Brilliant and light of wit" .)