You file a number (8)

I believe the answer is:

thousand

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'a number' is the definition.
(thousand is a kind of number)

'you file' is the wordplay.
'you' becomes 'thou' (I've seen this before).
'file' becomes 'sand' (I am not sure about this - if you are sure you should believe this answer much more).
'thou'+'sand'='THOUSAND'

Can you help me to learn more?

(Other definitions for thousand that I've seen before include "One and three zeros" , "quite a lot" , "See 1 down" , "Cardinal" , "M or K" .)

I've seen this clue in The Hindu.

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