The most common and most likely answer to this crossword clue is the 13 letter word ÃŽLE-DE-FRANCE
I've seen this crossword clue in The Guardian
Ã
Ž
L
E
-
D
E
-
F
R
A
N
C
E
More clues leading to the result ÃŽLE-DE-FRANCE
Buddy explains!
The straight part
We know that "area of the EU" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case area of the eu = ÃŽle-de-france.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.