Restoratives (6)
I believe the answer is:
tonics
'restoratives' is the definition.
(I know this)
This is all the clue.
(Other definitions for tonics that I've seen before include "Potions to strengthen and invigorate" , "Medicines or drinks with invigorating effects" , "contents of medicine cupboards" , "Keys" , "Pick-me-up drinks" .)