Driver disturbing trio most (8)
I believe the answer is:
motorist
'driver' is the definition.
(I know that motorist is a type of driver)
'disturbing trio most' is the wordplay.
'disturbing' indicates an anagram (I've seen this in other clues).
'trio'+'most'='triomost'
'triomost' anagrammed gives 'MOTORIST'.
(Other definitions for motorist that I've seen before include "One relying on car" , "Woman taking mini" , "Car driver" , "Car-driver" , "Traveller" .)