Minor rebuff (6)
I believe the answer is:
slight
I believe this is a double definition.
'minor' is the first definition.
(thesaurus)
'rebuff' is the second definition.
('slight' can be a synonym of 'rebuff')
(Other definitions for slight that I've seen before include "Small in degree; insult" , "Slim or tenuous" , "trivial" , "of no great significance" , "Small in extent" .)