Taxi feature (5)
I believe the answer is:
meter
'taxi feature' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for meter that I've seen before include "Apparatus for measuring" , "Instrument for measuring quantity" , "Something measuring" , "Measuring device as for electricity usage (5)" , "Device that measures, say, electricity usage" .)