Shocking, terrifying (8)
I believe the answer is:
horrific
I believe this clue is a double definition.
'shocking' is the first definition.
(thesaurus)
'terrifying' is the second definition.
(I've seen this before)
(Other definitions for horrific that I've seen before include "Causing fear" , "Dire" , "Shocking, disgusting" , "Arousing feelings of shock and fear" , "Frightful" .)