Clue: Devices for slowing down broadcast? Pauses in speech (3,6)
Answer: AIR BRAKES
Explanation: Definition: Devices for slowing down
A homophone ('broadcast') of AIR BREAKS ('pauses in speech'). I had to wait until solving 14A before deciding which was the answer and which the homophone – a common difficulty with this kind of clue, particularly here with the punctuation.