Cleaned but slightly burnt (7)
I believe the answer is:
charred
This clue is a double definition.
'cleaned' is the first definition.
(I've seen this before)
'slightly burnt' is the second definition.
(I've seen this before)
'but' is the link.
(Other definitions for charred that I've seen before include "what's black on surface" , "Blackened by fire" , "Partially burned" , "Partially burnt" , "Scorched and blackened" .)