Digit with its own rule? (5)
I believe the answer is:
thumb
'digit' is the definition.
(I know that thumb is a type of finger)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for thumb that I've seen before include "Quickly turn pages" , "Hitch-hiker's tool" , "Digit that enables grasping" , "Try to get a lift" , "One opposed to other manual workers" .)