Intimidating, threatening (8)
I believe the answer is:
menacing
I believe this clue is a double definition.
'intimidating' is the first definition.
(I've seen this before)
'threatening' is the second definition.
(I know that threatening can be written as menacing)
(Other definitions for menacing that I've seen before include "Ominous" , "Intimidating" , "Scary" , "Threatening" , "Suggesting danger" .)