Coach working on definite lines? (7)
I believe the answer is:
railcar
'coach working on definite lines?' is the definition.
'railcar' can be an answer for 'coach' (I've seen this before). I am not sure about the 'working on definite lines?' bit.
'coach working on' is the wordplay.
'coach' becomes 'car' (as in a train coach or car).
'working' becomes 'rail' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' is a charade indicator (letters next to each other).
'car' put after 'rail' is 'RAILCAR'.
Can you help me to learn more?
(Other definitions for railcar that I've seen before include "Passenger vehicle" , "form of transport" , "Powered train unit" , "Small train" , "coach" .)