Common seasoning (3-4)
'common seasoning' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for salt that I've seen before include "Crystalline substance used to season food" , "Common substance" , "Crystalline substance for the table" , "Seasoning; old sailor" , "Liveliness" .)
(Other definitions for sea-salt that I've seen before include "Substance from evaporating brine" , "Atlases (anag.)" , "Condiment from the briny" , "Evaporated brine product" , "Eat, lass! (anag) - something used when cooking" .)