Uncle Andrew keeping off the drugs (5)

I believe the answer is:

clean

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'off the drugs' is the definition.
I can't tell whether this definition defines the answer.

'uncle andrew keeping' is the wordplay.
'keeping' indicates a hidden word.
'CLEAN' can be found hidden inside 'uncle andrew'.

Can you help me to learn more?

(Other definitions for clean that I've seen before include "Squeaky?" , "Completely (colloq.), free of dirt" , "Quite" , "Untainted" , "Uncontaminated" .)

I've seen this clue in The Times.

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