Invention that restricts rear end chafing (8)
I believe the answer is:
'chafing' is the definition.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for friction that I've seen before include "Chafing -- disharmony" , "A rubbing between two surfaces" , "animosity" , "Sliding resistance" , "The rubbing of one thing against another, or quarrel between people" .)