Constraint some muesli mitigates (5)
I believe the answer is:
limit
'constraint' is the definition.
(I've seen this in another clue)
'some muesli mitigates' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'LIMIT' is hidden within 'muesli mitigates'.
(Other definitions for limit that I've seen before include "As far as something can go" , "Boundary or restriction" , "end" , "Confine to specific boundary" , "border" .)