Monastic wine? (4)

I believe the answer is:

asti

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

'wine?' is the definition.
(I've seen this before)

'monastic' is the wordplay.
'ASTI' is hidden in amongst the letters.
But, I am not sure how this is indicated.

Can you help me to learn more?

(Other definitions for asti that I've seen before include "- spumante, It. wine" , "Italian drunk" , "Italian product" , "18" , "Sparkling white wine" .)

I've seen this clue in the Evening Standard.

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