A single doctor, I have the right to go after a levy from a transport provider (4,6)
I believe the answer is:
taxi driver
'go after a levy from a transport provider' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'a single doctor i have the right' is the wordplay.
'a single' becomes 'taxi' (I can't justify this - if you can you should give a lot more credence to this answer).
'doctor' becomes 'Dr' (abbreviation).
'i have' becomes 'I've' (contraction of 'I have').
'the right' becomes 'r' (abbreviation).
'taxi'+'dr'+'ive'+'r'='TAXI-DRIVER'
'to' is the link.
Can you help me to learn more?
(Other definitions for taxi driver that I've seen before include "Road user" , "Cabbie" , "transport operator" .)