Good or bad sign (4)
I believe the answer is:
omen
'good or bad sign' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for omen that I've seen before include "Gloomy sign" , "Foreshadow" , "Sign of something about to happen" , "Foreboding" , "Sign of things to come" .)