Western capital in which you’ll find an appropriate leader (7)
I believe the answer is:
emperor
'leader' is the definition.
(I've seen this before)
'western capital in which you'll find an' is the wordplay.
I cannot quite understand how this works, but
'an' could be 'per' (synonymous as in 'once an hour', 'once per hour') and 'per' is located in the answer.
This explanation may well be incorrect...
'appropriate' acts as a link.
Can you help me to learn more?
(Other definitions for emperor that I've seen before include "Large richly-coloured butterfly" , "Absolute ruler" , "Ruler of large territory" , "Kaiser" , "Male ruler of a group of countries" .)