Provoke old party stump (6)
I believe the answer is:
offend
'provoke' is the definition.
(offending is a kind of provoking)
'old party stump' is the wordplay.
I cannot quite see how this works, but
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is present in the answer.
'party' could be 'ff' (I've seen this in other clues) and 'ff' is found within the answer.
The remaining letters 'end' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for offend that I've seen before include "Act in disregard of the law" , "Affront - break the law" , "Be displeasing to" , "Insult - act criminally" , "Wound (one's) feelings" .)