The most common and most likely answer to this crossword clue is the 6 plus 6 letter word BODICE RIPPER
I've seen this crossword clue in The Times
B
O
D
I
C
E
R
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P
P
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Buddy explains!
The straight part
We know that "sensational novel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sensational novel = bodice ripper.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.
What does BODICE RIPPER mean?
BODICE RIPPER noun- A romantic novel, usually in a historical setting, with frank depictions of sexual activity, especially one in which the female protagonist is seduced; (by extension) a film, television programme, etc., featuring such activity.