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' acts as a 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" .)