The most common and most likely answer to this crossword clue is the 5 plus 3 plus 5 letter word BREAK THE MOULD
I've seen this crossword clue in Financial Times
B
R
E
A
K
T
H
E
M
O
U
L
D
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.