Rotten tip giving insult (6)
I believe the answer is:
offend
'insult' is the definition.
(I've seen this before)
'rotten tip' is the wordplay.
'rotten' becomes 'off' (I've seen this before).
'tip' becomes 'end'.
'off'+'end'='OFFEND'
'giving' acts as a link.
(Other definitions for offend that I've seen before include "Hurt someone's feelings" , "Cause to feel hurt" , "Aggrieve" , "cause displeasure or do wrong" , "Upset - break the law" .)