Doctor Ron travelled by way of city (8)
I believe the answer is:
monrovia
'city' is the definition.
(Monrovia is an example)
'doctor ron travelled by way of' is the wordplay.
'doctor' becomes 'mo' (medical officer).
'travelled' indicates an anagram.
'by way of' becomes 'via' (via means by way of or by means of).
'ron' anagrammed gives 'nro'.
'mo'+'nro'+'via'='MONROVIA'
(Other definitions for monrovia that I've seen before include "African city" , "Capital of Liberia" , "Liberian capital" .)