Accelerator and choke (8)
I believe the answer is:
throttle
I believe this clue is a double definition.
'accelerator' is the first definition.
(synonyms)
'choke' is the second definition.
(I know that choke can be written as throttle)
'and' acts as a link.
(Other definitions for throttle that I've seen before include "Strangle the fuel valve" , "Check" , "Valve regulating volume of fuel and air" , "Strangle with car pedal?" , "Accelerator pedal" .)