Complains, ultimately taking offence (6)
I believe the answer is:
insult
'offence' is the definition.
(I know that insult is a type of offence)
'complains ultimately taking' is the wordplay.
'taking' indicates the answer is hidden within the clue (the answer is carried or taken by the clue).
'INSULT' is hidden within 'complains ultimately'.
(Other definitions for insult that I've seen before include "Abusive remark" , "Treat with abuse" , "Speak rudely or offensively about" , "Remark intended to hurt or humiliate" , "Treat disrespectfully" .)