Escape to form union (5)
I believe the answer is:
elope
'escape' is the definition.
(I've seen this in another clue)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for elope that I've seen before include "leave with lover" , "Run away with one's beloved" , "Do a runner" , "escape" , "Run away to wed" .)