The most common and most likely answer to this crossword clue is the 6 plus 6 letter word MARCEL PROUST
I've seen this crossword clue in Financial Times
M
A
R
C
E
L
P
R
O
U
S
T
More clues leading to the result MARCEL PROUST
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.