Accelerator pedal (8)
I believe the answer is:
throttle
'accelerator pedal' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for throttle that I've seen before include "Strangle; control (an engine)" , "Choke by pressure on the windpipe" , "Check" , "Strangle with car pedal?" , "Fuel-regulating valve in an engine" .)