Gossamer — transparent (8)
I believe the answer is:
cobwebby
This clue is a double definition.
'gossamer' is the first definition.
(I know that gossamer can be written as cobwebby)
'transparent' is the second definition.
(I know that transparent can be written as cobwebby)
(Other definitions for cobwebby that I've seen before include "Unclean (of corners in attics, perhaps?)" , "very fine?" , "needing new broom" , "Like an unswept corner" .)