Potion (6)
I believe the answer is:
elixir
'potion' is the definition.
(I know that elixir is a type of potion)
This is the entire clue.
(Other definitions for elixir that I've seen before include "Something believed to cure all ills" , "Miracle drug" , "Potion, panacea" , "Magic drink believed to cure all ills" , "Substance that cures all ills?" .)