It might cure shakes, a case in Lancet (4,4)
I believe the answer is:
rock salt
'it might cure' is the definition.
(rock salt might cure or preserve food)
'shakes a case in lancet' is the wordplay.
'shakes' becomes 'rocks' ('rock' can be a synonym of 'shake').
'case in' suggests removing the centre (the letters which encase the word are used).
'lancet' with its centre removed is 'lt'.
'rocks'+'a'+'lt'='ROCK-SALT'
(Other definitions for rock salt that I've seen before include "flavouring" , "Mineral sodium chloride" , "Mineral NaC One" , "Halite" , "Seasoning" .)