A rigorous preparation for toning the skin (10)

I believe the answer is:

astringent

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'preparation for toning the skin' is the definition.
I can't judge whether this defines the answer.

'a rigorous' is the wordplay.
'rigorous' becomes 'stringent' ('stringent' can be a synonym of 'rigorous').
'a'+'stringent'='ASTRINGENT'

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(Other definitions for astringent that I've seen before include "Caustic" , "for checking bleeding" , "biting" , "Scathing" , "Sharp or severe in manner" .)

I've seen this clue in The Telegraph.

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