Cost of food, on the quiet (5)
I believe the answer is:
price
'cost' is the definition.
(the cost or price of something)
'food on the quiet' is the wordplay.
'food' becomes 'rice' (rice is a food).
'on' means one lot of letters go next to another.
'the quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'rice' after 'p' is 'PRICE'.
'of' is the link.
(Other definitions for price that I've seen before include "Fee" , "Listed cost" , "Amount for which a thing is sold" , "Betting odds" , "Fanny?" .)