Cure-all mixture (6)
I believe the answer is:
elixir
'cure-all mixture' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for elixir that I've seen before include "Liquid supposed to prolong life in olden days" , "Substance that cures all ills?" , "Restorative drink" , "Drink once supposed to prolong life indefinitely" , "Quintessence" .)