Unglossy finish (5)
I believe the answer is:
matte
'unglossy finish' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for matte that I've seen before include "Mask used to block out areas of the image in filming" , "A dull finish" , "Dull, flat" , "Unusually dull" , "Mask used to add an image in front of camera" .)