Japanese capital until 1868 (5)
I believe the answer is:
kyoto
'japanese capital until 1868' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for kyoto that I've seen before include "Former Japanese capital city - Tokyo (anag)" , "Japanese capital before 1868" , "Japan's old capital" , "Japanese city of treaty on climate change" , "Old Japanese capital" .)