Predictive sign (4)
I believe the answer is:
omen
'predictive 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 "Warning - sign" , "Augur" , "Portent of things to come" , "Portent, prophetic indicator" , "Event regarded as a prophetic sign of good or evil" .)