The most common and most likely answer to this crossword clue is the 13 letter word UNFAMILIARITY
I've seen this crossword clue in The Daily Telegraph
U
N
F
A
M
I
L
I
A
R
I
T
Y
Buddy explains!
The straight part
We know that "it’s evident among strangers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s evident among strangers = unfamiliarity.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 UNFAMILIARITY mean?
UNFAMILIARITY noun- Lack of familiarity; ignorance or inexperience.