Daze or shock (4)
I believe the answer is:
This clue is a double definition.
'daze' is the first definition.
(I know that daze can be written as stun)
'shock' is the second definition.
(both can mean to surprise)
(Other definitions for stun that I've seen before include "Put out for the count" , "Daze, stupify" , "Daze, scatter senses" , "Shock or astonish" , "Daze or bewilder" .)