The most common and most likely answer to this crossword clue is the 10 plus 5 letter word EPISTOLARY NOVEL
I've seen this crossword clue in The Guardian
E
P
I
S
T
O
L
A
R
Y
N
O
V
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L
More clues leading to the result EPISTOLARY NOVEL
Buddy explains!
The straight part
We know that "literary work / literary work" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case literary work / literary work = epistolary novel.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.