The most common and most likely answer to this crossword clue is the 3 plus 2 plus 10 letter word ACT OF PARLIAMENT
A
C
T
O
F
P
A
R
L
I
A
M
E
N
T
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.