Drunken date getting stuck into beer where the floor may start to sway! (4,4)

'where the floor may start to sway' is the definition.
(a boat may sway)

'drunken date getting stuck into beer' is the wordplay.
'drunken' is an anagram indicator.
'getting stuck into' indicates putting letters inside.
'beer' becomes 'bock' (bock is a kind of beer).
'date' is an anagram of 'atde'.
'atde' inserted inside 'bock' is 'BOAT DECK'.