Be quiet and have a drink outside cabin (4,2)
I believe the answer is:
shut up
'be quiet' is the definition.
(synonyms)
'have a drink outside cabin' is the wordplay.
'have a drink' becomes 'sup' (I've seen this in other clues).
'outside' means one lot of letters goes inside another.
'cabin' becomes 'hut' (I've seen this in another clue).
'sup' placed around 'hut' is 'SHUT UP'.
'and' acts as a link.
(Other definitions for shut up that I've seen before include "Keep mum" , "Rude order to stop talking" , "Keep quiet!" , "close completely?" , "Closely confined" .)