I appreciate that company's Mexican food (4)
I believe the answer is:
taco
'mexican food' is the definition.
(type of Mexican snack)
'i appreciate that company's' is the wordplay.
'i appreciate that' becomes 'ta' (informal way of saying thank you).
'company' becomes 'co' (abbreviation).
'ta'+'co'='TACO'
(Other definitions for taco that I've seen before include "Filled tortilla roll" , "Filled rolled tortilla" , "Mexican snack" , "Tortilla rolled round a filling" , "Tortilla with savoury filling" .)