Finished going up road, I have top gear (9)
I believe the answer is:
overdrive
'top gear' is the definition.
'finished going up road i have' is the wordplay.
'finished' becomes 'over' ('over' can be similar in meaning to 'finished').
'going up' says the letters should be written backwards.
'road' becomes 'rd' (abbreviation).
'i have' becomes 'ive'.
'rd' backwards is 'dr'.
'over'+'dr'+'ive'='OVERDRIVE'
(Other definitions for overdrive that I've seen before include "gear for cruising" , "It gets you going fast" , "Engine mechanism" , "State of excessive activity" , "State of frantic activity" .)