Sheen, gloss (6)
I believe the answer is:
lustre
I believe this clue is a double definition.
'sheen' is the first definition.
(I know that sheen can be written as lustre)
'gloss' is the second definition.
(I've seen this before)
(Other definitions for lustre that I've seen before include "brilliance" , "Prestige" , "Distinction < in five years" , "effect of reflected light" , "Sheen - glaze" .)