The most common and most likely answer to this crossword clue is the 8 letter word INTEGERS
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Buddy explains!

The straight part
We know that "Say, thousand and one" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case say, thousand and one = integers.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 INTEGERS mean?
INTEGERS noun- A number that is not a fraction; an element of the infinite and numerable set {..., -3, -2, -1, 0, 1, 2, 3, ...}.
- The smallest ring containing the natural numbers; the set {... -3, -2, -1, 0, 1, 2, 3 ...}.