Comments about stains (7)
I believe the answer is:
remarks
'comments' is the definition.
('remark' can be a synonym of 'comment')
'about stains' is the wordplay.
'about' becomes 're' (regarding).
'stains' becomes 'marks' ('mark' can be a synonym of 'stain').
're'+'marks'='REMARKS'
(Other definitions for remarks that I've seen before include "See 14" , "Comments, observations" .)