National borders ignored by EU country (5)
I believe the answer is:
omani
'national borders ignored' is the definition.
I can't tell whether this defines the answer.
'by eu country' is the wordplay.
'by' says to put letters next to each other.
'eu' becomes 'i' (I can't justify this - if you can you should give a lot more credence to this answer).
'country' becomes 'oman' (Oman is an example).
'i' after 'oman' is 'OMANI'.
Can you help me to learn more?
(Other definitions for omani that I've seen before include "one from the Middle East" , "Naomi (anag) -- from Muscat?" , "Inhabitant of Middle Eastern sultanate" , "Native of one Arabian sultanate" , "Someone from Muscat" .)