Paint applied with a glossy coat (6)
I believe the answer is:
patina
'glossy coat' is the definition.
'paint applied with a' is the wordplay.
'applied with' indicates anagramming the letters.
'paint' with its letters mixed up with 'a' gives 'PATINA'.
(Other definitions for patina that I've seen before include "Green coating on bronze" , "Surface shine" , "Brownish surface film on old bronze" , "Surface film formed by age" , "Sheen acquired from constant handling" .)