Slows down and snaps on the radio (6)
I believe the answer is:
brakes
'slows down' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for brakes that I've seen before include "In a way, stops" , "Apply them to slow down" , "Slowing or stopping devices" , "Thickets of brush or briars" , "Vehicle's stopping mechanism" .)