The most common and most likely answer to this crossword clue is the 8 letter word ESTONIAN
I've seen this crossword clue in The Daily Telegraph
E
S
T
O
N
I
A
N
More clues leading to the result ESTONIAN
- Established working name for language
- European nations upset after vote, ultimately
- High tension surrounding one European language
- National service initially embraced by schoolboy
- Head of school entertained by schoolboy language
- Stone circles one by one revealing Uralic language
- Perhaps Boris Johnson welcomes special European
- College member acquiring second language
- Public school boy boxing second European
- Schoolboy boxing southern European
Buddy explains!

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