Also known to fit in a beer mug (6)

I believe the answer is:

beaker

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

'also known to fit in a beer' is the wordplay.
'also known' becomes 'ak' (this might be a standard abbreviation of which I'm unaware).
'to fit in' indicates putting letters inside.
'ak' inserted within 'beer' is 'BEAKER'.

Can you help me to learn more?

(Other definitions for beaker that I've seen before include "Glass vessel" , "Mug - large glass" , "Cup with a wide mouth" , "Open glass, straight with lip, used in laboratory" , "Plastic mug" .)

I've seen this clue in the Sydney Morning Herald.

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