Deny it's rubbish (6)
I believe the answer is:
refuse
I believe this is a double definition.
'deny' is the first definition.
(deny can mean to refuse or reject)
'rubbish' is the second definition.
(refuse can mean rubbish or garbage)
'it's' is the link.
(Other definitions for refuse that I've seen before include "Say no to - rubbish" , "Decline to jump; rubbish" , "litter" , "Don't take the rubbish" , "Decline to take the rubbish" .)