The most common and most likely answer to this crossword clue is the 3 plus 3 plus 5 plus 4 letter word ONE TWO THREE FOUR
I've seen this crossword clue in The Guardian
O
N
E
T
W
O
T
H
R
E
E
F
O
U
R
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.