Tonic (4-2-2)
I believe the answer is:
pick-me-up
'tonic' is the definition.
(I know that pick-me-up is a type of tonic)
This is the entire clue.
(Other definitions for pick-me-up that I've seen before include "Stimulating drink" , "A restorative tonic drink" , "A tonic to restore health or relieve depression" , "Stimulative drink" , "Medicinal tonic" .)