It makes nine by itself (5)

I believe the answer is:

three

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'it makes nine by itself' is the definition.
The definition suggests a singular noun which matches the answer.

This is all the clue.

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(Other definitions for three that I've seen before include "Prime number" , "Number of strikes before you're out" , "Bears or blind mice" , "Small number that still makes a crowd?" , "Number of Dumas's musketeers" .)

I've seen this clue in The Irish Times.

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