Spooky sightings (4)
I believe the answer is:
ufos
'spooky sightings' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ufos that I've seen before include "Initially and formally, flying saucers" , "Mysterious phenomena" , "Initially, official flying saucers" , "Potential alien craft" , "Initially, formal flying saucers" .)