Deny it's rubbish (6)
I believe the answer is:
refuse
This clue is a double definition.
'deny' is the first definition.
(deny can mean to refuse or reject)
'rubbish' is the second definition.
(both can mean waste material)
'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" .)