Cause continuing annoyance or resentment (6)
I believe the answer is:
rankle
'cause continuing annoyance or resentment' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rankle that I've seen before include "Eat into and cause resentment" , "get someone's goat" , "keep hurting" , "will continue to cause irritation" , "Continue vexing" .)