Mutter, being made ill with inn food (9)
I believe the answer is:
nutriment
'food' is the definition.
(I know that nutriment is a type of food)
'mutter being made ill with inn' is the wordplay.
I cannot quite see how this works, but
'being' could be 'nut' (nut is a kind of being) and 'nut' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for nutriment that I've seen before include "It sustains" , "Material providing food" , "diet" , "Sustenance, nourishment" , "Nourishing food" .)