Salt in treat specially cooked (7)
I believe the answer is:
nitrate
'salt' is the definition.
(nitrate is a kind of salt)
'in treat specially cooked' is the wordplay.
'specially cooked' indicates anagramming the letters (I've seen this in other clues).
'in'+'treat'='intreat'
'intreat' anagrammed gives 'NITRATE'.
(Other definitions for nitrate that I've seen before include "Fertilizer" , "Tear tin up for fertiliser" , "Natural or synthetic fertiliser" , "Compound" , "Nattier (anag.)" .)