In a scary way (6)
I believe the answer is:
eerily
'in a scary way' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eerily that I've seen before include "In a strange and frightening manner" , "in a weird way" , "Weirdly, frighteningly" , "how to seem frightening" , "In an unnatural manner" .)