Muesli ingredients (4)
I believe the answer is:
oats
'muesli ingredients' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oats that I've seen before include "Young men sow wild ones" , "Cereal food for horses" , "Grains used as food and fodder" , "Basis of porridge" , "Cereal grass and seeds" .)