The most common and most likely answer to this crossword clue is the 12 letter word SCANDINAVIAN
S
C
A
N
D
I
N
A
V
I
A
N
More clues leading to the result SCANDINAVIAN
- Read documents about overthrow of a ruler, north European
- Investigate loud noise of birds — Swedish, possibly
- Swede possibly travelling in Canada is extremely vain
- Study noise of birds from Northern Europe
- Study noise of birds from part of Europe
- Study clamour of birds in northern Europe?
- European survey on noise of birds
Buddy explains!

The straight part
We know that "European" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case european = scandinavian.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.