Having toured railway, promote test drive (3,3)
I believe the answer is:
try out
'test drive' is the definition.
'try out' can be an answer for 'test' (try out can mean to test or trial). I'm not sure about the 'drive' bit.
'having toured railway promote' is the wordplay.
I cannot really see how this works, but
'railway' could be 'ry' (abbreviation for railway) and 'ry' is found in the answer.
'promote' could be 'tout' (I've seen this in another clue) and 'tout' is found within the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for try out that I've seen before include "Put to experimental use" , "Test and evaluate" , "Taste" , "Sample" .)