Junk? Nonsense! (7)
I believe the answer is:
rubbish
I believe this clue is a double definition.
'junk?' is the first definition.
(junk is a kind of rubbish)
'nonsense' is the second definition.
(I've seen this before)
(Other definitions for rubbish that I've seen before include "Worthless material to discard" , "Refuse, junk" , "Trash - nonsense" , "Waste; very bad (colloq.)" , "Nonsense; very bad" .)