Final sprinkling of salt (4)
I believe the answer is:
last
'final' is the definition.
(synonyms)
'sprinkling of salt' is the wordplay.
'sprinkling of' indicates anagramming the letters (the letters are sprinkled or scattered around).
'salt' is an anagram of 'LAST'.
(Other definitions for last that I've seen before include "Bringing up the rear" , "Form on which a shoe is made" , "Latest" , "Survive; after all others" , "Endure - this clue is!" .)