Unimaginative European leaving dispute with Luxembourg (4)
I believe the answer is:
dull
'unimaginative' is the definition.
(synonyms)
'european leaving dispute with luxembourg' is the wordplay.
'european leaving dispute' becomes 'dul' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' means one lot of letters go next to another.
'luxembourg' becomes 'L' (international vehicle registration code).
'dul'+'l'='DULL'
Can you help me to learn more?
(Other definitions for dull that I've seen before include "Boring - not sunny" , "Lacklustre" , "Drab" , "Uninspiring" , "Matt; overcast" .)