Gentle sheen (6)
I believe the answer is:
lustre
'gentle sheen' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lustre that I've seen before include "Brilliancy" , "Prestige" , "Gentle sheen/glow" , "Distinction < in five years" , "Gentle sheen, soft glow" .)