Digit going up or down in verdict (5)
I believe the answer is:
thumb
'digit' is the definition.
(I know that thumb is a type of finger)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for thumb that I've seen before include "Travel by . . . . . - hitchhike" , "Travel by getting free rides from motorists" , "Digit (used for making a hitch?)" , "Indicate need for lift" , "''Tom ..., the piper's son'' (nursery rhyme)" .)