Cover up, as wrongdoing
I believe the answer is:
whitewash
'cover up as wrongdoing' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for whitewash that I've seen before include "Wall pigment; defeat" , "Gloss over faults with wall colouring?" , "Gloss over, suppress" , "Substance applied to a wall - total defeat" , "Lime solution; cover up" .)