Distilled spirit in a gram can (8)

I believe the answer is:

armagnac

I'm a little stuck... Click here to teach me more about this clue!

'spirit in a gram can' is the definition.
'armagnac' can be an answer for 'spirit' (I've seen this before). I'm unsure of the 'in a gram can' bit.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for armagnac that I've seen before include "Kind of brandy" , "A gram can for a French brandy" , "Spirit" , "Liquor" , "Type of brandy" .)

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

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