The most common and most likely answer to this crossword clue is the 8 plus 4 letter word MONETARY UNIT
I've seen this crossword clue in Financial Times
M
O
N
E
T
A
R
Y
U
N
I
T
More clues leading to the result MONETARY UNIT
Buddy explains!

The straight part
We know that "euro, maybe" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case euro, maybe = monetary unit.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.