Decorator presses buzzer to get drink (3,4)
I believe the answer is:
ice beer
'drink' is the definition.
(I have seen 'strong drink' mean 'ice beer' so perhaps 'drink' could also mean 'ice beer')
'decorator presses buzzer' is the wordplay.
'decorator' becomes 'icer' (some decorating a cake with icing).
'presses' means one lot of letters goes inside another (some letters are pressed between others).
'buzzer' becomes 'bee' (insect which buzzes).
'icer' enclosing 'bee' is 'ICE BEER'.
'to get' acts as a link.
(Another definition for ice beer that I've seen is " strong drink".)