Nutter taking two addictive drugs (8)

I believe the answer is:

crackpot

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'nutter taking two' is the definition.
I can't tell whether this defines the answer.

'addictive drugs' is the wordplay.
'addictive' becomes 'crack' (I can't justify this - if you can you should give a lot more credence to this answer).
'drugs' becomes 'pot' (slang term for mariujana).
'crack'+'pot'='CRACKPOT'

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(Other definitions for crackpot that I've seen before include "Idiot" , "Eccentric; impractical" , "Ridiculous" , "Informal eccentric like damaged utensil" , "Nutty" .)

I've seen this clue in The Times.

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