Intense fear or shock (6)
I believe the answer is:
horror
This clue is a double definition.
'intense fear' is the first definition.
(I've seen this before)
'shock' is the second definition.
(I have seen 'Intense shock ' mean 'horror' so perhaps 'shock' could also mean 'horror')
(Other definitions for horror that I've seen before include "Extreme fright and revulsion" , "Terror; film genre" , "Great fear and abhorrence" , "Intense shock" , "'Repugnance, revulsion (6)'" .)