Transport Authority with power to chase criminals (3)
I believe the answer is:
cab
'transport' is the definition.
(cab is a kind of transport)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for cab that I've seen before include "info for citizens provided here" , "'The authority collects money made from crime, initially (3)'" , "Driving compartment" , "An American taxi" , "vehicle" .)