The most common and most likely answer to this crossword clue is the 9 plus 9 letter word PAKISTANI PAKISTANI
P
A
K
I
S
T
A
N
I
P
A
K
I
S
T
A
N
I
Buddy explains!
The straight part
We know that "Neighbour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case neighbour = pakistani pakistani.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.