Bit of a step up for taxi drivers, vintage car ultimately (5)
I believe the answer is:
riser
'bit of a step up' is the definition.
(part of a stair)
'for taxi drivers vintage car ultimately' is the wordplay.
'ultimately' says to take the final letters.
The final letters of 'for taxi drivers vintage car' are 'RISER'.
(Other definitions for riser that I've seen before include "Vertical piece between stair steps" , "Vertical part of a stair or step" , "person advancing position?" , "Upright piece between steps" , "Bit of a step up?" .)