Final use of salt (4)
I believe the answer is:
last
'final' is the definition.
('last' can be a synonym of 'final')
'use of salt' is the wordplay.
'use of' indicates anagramming the letters.
'salt' anagrammed gives 'LAST'.
(Other definitions for last that I've seen before include "It helps cobbler" , "` `Let the cobbler stick to his ....' '" , "The cobbler's equipment will endure" , "stay at the back" , "nowhere near winning Miss World?" .)