Escape to establish a union (5)
I believe the answer is:
elope
'escape' is the definition.
(I know that elope is a more specific form of the action flee)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for elope that I've seen before include "Bolt" , "go off to the match?" , "Run off with Mr/Ms Right" , "Run away with lover" , "Run away secretly to marry" .)