Confined by fixed rota, cultivate food in Mexico (8)
I believe the answer is:
tortilla
'food in mexico' is the definition.
(tortillas are flatbreads eaten in Mexico)
'confined by fixed rota cultivate' is the wordplay.
'confined by' indicates putting letters inside.
'fixed' indicates anagramming the letters.
'cultivate' becomes 'till' (I've seen this before).
'rota' with letters rearranged gives 'tora'.
'tora' going around 'till' is 'TORTILLA'.
(Other definitions for tortilla that I've seen before include "Mexican dish" , "Thin unleavened pancake" , "Mexican filled pancake" , "Cake including maize" , "Mexican maize pancake" .)