Food's standard of niceness (3)
I believe the answer is:
pie
'food's' is the definition.
(pie is a kind of food)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for pie that I've seen before include "Dish baked in pastry-lined pan" , "Filled pastry" , "See 6" , "Very easy answer as" , "In the sky, it's an empty promise" .)