Contumely (6)
I believe the answer is:
insult
'contumely' is the definition.
(I know that contumely can be written as insult)
This is all the clue.
(Other definitions for insult that I've seen before include "A deliberately offensive remark" , "Slander" , "Treat disrespectfully" , "Demeaning remark" , "Remark intended to hurt or humiliate" .)