The most common and most likely answer to this crossword clue is the 3 plus 3 plus 3 plus 3 plus 8 letter word PUT TWO AND TWO TOGETHER
I've seen this crossword clue in The Guardian
P
U
T
T
W
O
A
N
D
T
W
O
T
O
G
E
T
H
E
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.