Tonic going up and down (7)
I believe the answer is:
reviver
'tonic' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for reviver that I've seen before include "Tonic" , "Pick-me-up" , "One who resuscitates" , "Restorer to life" .)