Lacquer (7)
I believe the answer is:
varnish
'lacquer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for varnish that I've seen before include "Hard, lustrous, transparent finish to a surface" , "Shiny transparent coating used on wood" , "'Hard, transparent finish to a surface (7)'" , "Glossy stain" , "Apply hard shiny stuff to wooden surface" .)