Made from the one mad drug treatment (9)

I believe the answer is:

methadone

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'drug treatment' is the definition.
'methadone' can be an answer for 'drug' (I've seen this before). I am not certain of the 'treatment' bit.

'made from the one mad' is the wordplay.
'made from' is an anagram indicator.
'the'+'one'+'mad'='theonemad'
'theonemad' with letters rearranged gives 'METHADONE'.

Can you help me to learn more?

(Other definitions for methadone that I've seen before include "Synthetic analgesic" , "Narcotic analgesic drug" , "Synthetic drug taken to replace heroin" , "Drug used in treating heroin addiction" .)

I've seen this clue in the Sydney Morning Herald.

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