Alarmist (11)
I believe the answer is:
scaremonger
'alarmist' is the definition.
(scaremonger is a kind of alarmist)
This is all the clue.
(Other definitions for scaremonger that I've seen before include "agitator" , "Spreader of frightening rumours" , "One spreading worrying rumours" , "Spreader of panic" , "Alarmist" .)