Kings take this route in London (3)
I believe the answer is:
way
'route in london' is the definition.
'way' can be an answer for 'route' (thesaurus). I am not sure about the 'in london' bit.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for way that I've seen before include "Manner; road" , "Path" , "Route; direction" , "Street" , "Method; route" .)