In which one suffered from decimation! (3)

I believe the answer is:

ten

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'in which one suffered from decimation' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Maybe there's an association between them I don't understand?

This is all the clue.

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(Other definitions for ten that I've seen before include "Base of decimal system" , "Dudley Moore/Bo Derek film" , "Figure" , "Roman numeral X" , "X-WORD" .)

I've seen this clue in the Evening Standard.

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