Fan making one replace old cassava root (6)

I believe the answer is:

maniac

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'fan' is the definition.
(thesaurus)

'one replace old cassava root' is the wordplay.
'one replace old' becomes 'mania' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'root' indicates taking the first letters (I've seen 'root of' mean this).
The first letter of 'cassava' is 'c'.
'mania'+'c'='MANIAC'

'making' is the link.

Can you help me to learn more?

(Other definitions for maniac that I've seen before include "fruitcake?" , "Deranged person" , "Insane person" , "One behaves wildly or with excessive enthusiasm" , "Nutter" .)

I've seen this clue in The Hindu.

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