The most common and most likely answer to this crossword clue is the 11 letter word SCRATCHPADS
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Buddy explains!

The straight part
We know that "notebooks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case notebooks = scratchpads.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 SCRATCHPADS mean?
SCRATCHPADS noun- A pad of paper for preliminary notes or sketches or writings, etc.
- (in transaction processing systems) A piece of temporary memory to hold details of a current conversation, usually scratchpad memory.