Gloss over (9)
I believe the answer is:
whitewash
'gloss over' is the definition.
(I know that gloss over can be written as whitewash)
This is the entire clue.
(Other definitions for whitewash that I've seen before include "overwhelming defeat" , "Lime solution; cover up" , "Cover-up -- wall coating" , "Gloss over faults with wall colouring?" , "Substance applied to a wall - total defeat" .)