Flee with a fastener (4)
I believe the answer is:
bolt
I believe this is a double definition.
'flee' is the first definition.
(I know that bolt is a more specific form of flee)
'fastener' is the second definition.
(bolt is a kind of fastener)
'with a' acts as a link.
(Other definitions for bolt that I've seen before include "Flash of lightening - run away" , "playwright" , "Eat hurriedly" , "eat food quickly and > lock up" , "for security reasons" .)