Anger or annoy (3)
I believe the answer is:
vex
This clue is a double definition.
'anger' is the first definition.
(I've seen this in another clue)
'annoy' is the second definition.
(I know that annoy can be written as vex)
(Other definitions for vex that I've seen before include "upset" , "Irritate, annoy" , "Irk" .)