The most common and most likely answer to this crossword clue is the 3 plus 2 plus 3 plus 3 plus 3 plus 5 letter word ONE IS ONE AND ALL ALONE
I've seen this crossword clue in Independent
O
N
E
I
S
O
N
E
A
N
D
A
L
L
A
L
O
N
E
Buddy explains!
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.