Oaty breakfast mix (6)
I believe the answer is:
muesli
'oaty breakfast mix' 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 "Breakfast mixture of dry cereals and fruits" , "Type of breakfast cereal" , "Breakfast mix of oats, nuts, fruit etc" , "Mixture of crushed cereals. nuts and fruit" , "Granola-like food" .)