Crossword Genius

Fill mug up (4)

Ross

I believe the answer is:

cram

I believe this clue is a double definition.

'fill' is the first definition.
('cram' can be a synonym of 'fill')

'mug up' is the second definition.
('cram' can be a synonym of 'mug up')

(Other definitions for cram that I've seen before include "jam" , "Quickly learn - stuff" , "Study hard for exam" , "Crowd or pack to capacity" , "Stuff; study hard" .)

I've seen this clue in The Times.
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