The most common and most likely answer to this crossword clue is the 5 plus 3 plus 3 plus 4 letter word WHATS THE BIG IDEA
I've seen this crossword clue in Independent
W
H
A
T
S
T
H
E
B
I
G
I
D
E
A
More clues leading to the result WHATS THE BIG IDEA
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.