Tips off (6)
I believe the answer is:
alerts
'tips off' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for alerts that I've seen before include "Puts on guard, warns about impending danger" , "Warns, draws attention to" , "Puts on guard, forewarns" , "Warnings" , "Alarms, warning signals" .)