The most common and most likely answer to this crossword clue is the 9 letter word PLETHORAS
P
L
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T
H
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A
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Buddy explains!
The straight part
We know that "Large numbers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case large numbers = plethoras.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 PLETHORAS mean?
PLETHORAS noun- (usually followed by of) An excessive amount or number; an abundance.
- An excess of red blood cells or bodily humours.