Covers food in tin with ordinary salt (8)
I believe the answer is:
canopies
'covers' is the definition.
(canopying is a kind of covering)
'food in tin with ordinary salt' is the wordplay.
'food' becomes 'pie' (pie is a kind of food).
'in' is an insertion indicator.
'tin' becomes 'can' ('can' can be a synonym of 'tin').
'with' says to put letters next to each other.
'ordinary salt' becomes 'os' (this might be a standard abbreviation of which I'm unaware).
'can'+'os'='canos'
'pie' inserted inside 'canos' is 'CANOPIES'.
(Other definitions for canopies that I've seen before include "Coverings to shelter an area from the weather" , "Coverings over a bed, throne, etc." .)