Ferment help for a mixologist (7)

I believe the answer is:

barmaid

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'for a mixologist' is the definition.
(barmaid is a kind of mixologist)

'ferment help' is the wordplay.
'ferment' becomes 'barm' (I am not sure about this - if you are sure you should believe this answer much more).
'help' becomes 'aid' (synonyms).
'barm'+'aid'='BARMAID'

Can you help me to learn more?

(Other definitions for barmaid that I've seen before include "She serves drinks" , "Pub girl" , "Female serving drinks" , "serving lady" , "Pub employee" .)

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

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