Breakfast bowlful (6)
I believe the answer is:
muesli
'breakfast bowlful' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for muesli that I've seen before include "Mule is fed with breakfast compound" , "Mixture of cereals etc" , "Swiss cereal" , "Rolled oats, nuts and fruit mixture" , "Swiss breakfast?" .)