Leave rubbish out (4,3)
I believe the answer is:
bunk off
'leave' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'rubbish out' is the wordplay.
'rubbish' becomes 'bunk' (both can mean nonsense).
'out' becomes 'off' (I've seen this before).
'bunk'+'off'='BUNK OFF'
Can you help me to learn more?
(Other definitions for bunk off that I've seen before include "Play truant" , "Abscond (from school)" .)