The most common and most likely answer to this crossword clue is the 10 letter word POTBOILERS
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More clues leading to the result POTBOILERS
Buddy explains!

The straight part
We know that "popular books" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case popular books = potboilers.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 POTBOILERS mean?
POTBOILERS noun- (mildly) A creative work of low quality (book, art, etc), produced merely to earn a living or for profit, as opposed to serious creative expression.
- A stone used to transfer heat from a fire into a vessel of water, so as to heat the contents.