Swot with drinking vessel raised (3,2)
I believe the answer is:
mug up
'swot' is the definition.
(synonyms)
'with drinking vessel raised' is the wordplay.
'with' says to put letters next to each other.
'drinking vessel' becomes 'mug' (mug is a kind of drinking vessel).
'raised' becomes 'up' (similar in meaning).
'mug' put next to 'up' is 'MUG UP'.
(Other definitions for mug up that I've seen before include "Study quickly (for, eg, an exam)" , "Learn quickly (for exam)" , "Study hard" , "Quickly revise" , "Learn subject rapidly" .)