Not a serious affront? (6)
I believe the answer is:
slight
'affront?' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for slight that I've seen before include "Put down" , "Minor - offence" , "Deliberately discourteous act" , "Not strongly built" , "Slim or tenuous" .)