Foreboding, portentous (7)
I believe the answer is:
ominous
I believe this clue is a double definition.
'foreboding' is the first definition.
(I've seen this in another clue)
'portentous' is the second definition.
(I've seen this before)
(Other definitions for ominous that I've seen before include "Menacing, sinister" , "Threatening or foreshadowing evil or tragedy" , "Inauspicious" , "Portending evil" , "Looking like trouble coming" .)