I say you interrupt me with half slices of breakfast food (6)
I believe the answer is:
muesli
'breakfast food' is the definition.
(I know that muesli is a type of breakfast food)
'i say you interrupt me with half slices' is the wordplay.
'i say you' becomes 'u' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'interrupt' means one lot of letters goes inside another.
'with' says to put letters next to each other.
'half' means to take half the letters.
'u' going into 'me' is 'mue'.
'slices' halved is 'sli'.
'mue'+'sli'='MUESLI'
'of' is the link.
Can you help me to learn more?
(Other definitions for muesli that I've seen before include "Mixture of crushed grain, nuts etc" , "Swiss breakfast?" , "Breakfast dish of cereal, dried fruit and nuts in milk" , "healthy breakfast?" , "Type of breakfast cereal" .)