Excellent drink — get round in (4-2)
I believe the answer is:
slap-up
'excellent' is the definition.
(I've seen this before)
'drink get round in' is the wordplay.
'drink' becomes 'lap' (to lap is to drink up).
'get round' becomes 'sup' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'lap' put within 'sup' is 'SLAP-UP'.
Can you help me to learn more?
(Other definitions for slap-up that I've seen before include "With no expense spared" , "Very good, meal say" , "Lavish, meal say" , "Luxurious (feast)" , "Lavish (colloq.)" .)