This drink can go a hundred years back (6)

I believe the answer is:

cognac

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'this drink' is the definition.
(Cognac is an example)

'can go a hundred years back' is the wordplay.
'a hundred years' becomes 'c' (I am not sure about this - if you are sure you should believe this answer much more).
'back' says the letters should be written backwards.
'can'+'go'+'c'='cangoc'
'cangoc' written backwards gives 'COGNAC'.

Can you help me to learn more?

(Other definitions for cognac that I've seen before include "Liquor" , "French brandy region" , "strong drink" , "Brandy of the French Charente" , "Type of brandy" .)

I've seen this clue in The Globe and Mail.

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