Warning from a driver? (4)
I believe the answer is:
fore
'warning from a driver?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for fore that I've seen before include "Warning cry of golfer" , "Not aft" , "Golfer's shouted warning" , "Golfer's warning shout" , "Warning cry on a golf course" .)