Breakfast nonsense? (6)
I believe the answer is:
waffle
I believe this clue is a double definition.
'breakfast' is the first definition.
(item which might be eaten at breakfast)
'nonsense?' is the second definition.
(I know that waffle is a type of nonsense)
(Other definitions for waffle that I've seen before include "Trivial talk; cake" , "Wordy talk or a small cake eaten hot" , "Vacillating talk" , "Type of pancake and uninteresting talk" , "Meaningless verbiage" .)