Rustic green food mushed up, mutant leaving upset stomach (7)
I believe the answer is:
peasant
'rustic' is the definition.
(peasant is a kind of rustic)
'green food mushed up mutant leaving upset stomach' is the wordplay.
I cannot quite understand how this works, but
'green' could be 'pea' (pea green is a kind of green) and 'pea' is found in the answer.
'food' could be 'a' (A is an example) and 'a' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for peasant that I've seen before include "Revolting person" , "Yokel" , "Lowly 20 worker" , "Poor rustic" , "Rustic fellow" .)