Say no to rubbish (6)
I believe the answer is:
refuse
This clue is a double definition.
'say no' is the first definition.
(I've seen this before)
'to rubbish' is the second definition.
(both can mean waste material)
(Other definitions for refuse that I've seen before include "Decline, repudiate" , "Deny; rubbish" , "Say no to - waste" , "Say no to - rubbish" , "'Deny, turn down (6)'" .)