The most common and most likely answer to this crossword clue is the 10 letter word EXTRANEOUS
I've seen this crossword clue in The Times
E
X
T
R
A
N
E
O
U
S
More clues leading to the result EXTRANEOUS
- Changing euro next, as foreign
- More intelligence keeps European outside
- Sex out near rocks ‘inappropriate‘
- Foreign newspaper’s special edition, with sense about English
- Strange scoreboard entry attached to the bridge player entertained by us in France
- More sense to conserve energy that's unnecessary
- Particularly sound judgment, English admitted, not essential
Buddy explains!
The straight part
We know that "not essential" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not essential = extraneous.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.
What does EXTRANEOUS mean?
EXTRANEOUS adjective- Not belonging to, or dependent upon, a thing; without or beyond a thing; foreign
- Not essential or intrinsic