Ban EU travel until, finally, non-existent (4)
I believe the answer is:
null
'non-existent' is the definition.
I can't judge whether this definition defines the answer.
'ban eu travel until finally' is the wordplay.
'finally' says to take the final letters.
The final letters of 'ban eu travel until' are 'NULL'.
Can you help me to learn more?
(Other definitions for null that I've seen before include "Legally void" , "Immaterial and void" , "Of no effect, value" , "Without value or consequence" , "Invalid; empty" .)