Hitch-hiker's request for a tonic? (4-2-2)
I believe the answer is:
pick-me-up
'for a tonic?' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for pick-me-up that I've seen before include "Stimulating drink" , "A tonic to restore health or relieve depression" , "Stimulant" , "Medicinal tonic" , "Stimulative drink" .)