Impaired, spoilt (6)
I believe the answer is:
marred
This clue is a double definition.
'impaired' is the first definition.
('mar' can be a synonym of 'impair')
'spoilt' is the second definition.
('mar' can be a synonym of 'spoil')
(Other definitions for marred that I've seen before include "'Impaired, spoilt (6)'" , "Blemished" , "Damaged or spoiled" .)