Comment about brand (6)
I believe the answer is:
remark
'comment' is the definition.
('remark' can be a synonym of 'comment')
'about brand' is the wordplay.
'about' becomes 're' (regarding).
'brand' becomes 'mark' ('mark' can be a synonym of 'brand'**).
're'+'mark'='REMARK'
(Other definitions for remark that I've seen before include "Say as a comment" , "Notice; happen to say" , "Something said; take notice of" , "Observation - notice" , "what someone says?" .)