Leave in a hurry (4)
I believe the answer is:
bolt
'leave in a hurry' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bolt that I've seen before include "Fastener; suddenly run away" , "one may be shot" , "A . . . . from the blue is a complete surprise" , "From the blue, it's a big surprise" , "Fasten - flee" .)