The most common and most likely answer to this crossword clue is the 4 plus 6 plus 5 letter word TAKE FRENCH LEAVE
I've seen this crossword clue in The Times
T
A
K
E
F
R
E
N
C
H
L
E
A
V
E
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.