Last order for sailor (4)
'sailor' is the definition.
(salt is a kind of sailor)
'last order' is the wordplay.
'order' is an anagram indicator.
'last' is an anagram of 'SALT'.
'for' is the link.
(Other definitions for salt that I've seen before include "NaCl", "Sea dog", "Crystalline substance for the table", "Seasoning; old sailor", "A defence against ice".)