Seat individual inside capital city (5)
I believe the answer is:
sofia
This clue could be a double definition.
'seat individual' is the first definition.
'sofia' can be an answer for 'seat' (I have seen 'seat of government' mean 'sofia' so perhaps 'seat' could also mean 'sofia'). I am not sure about the 'individual' bit.
'capital city' is the second definition.
(I've seen this before)
'inside' is the link.
Can you help me to learn more?
(Other definitions for sofia that I've seen before include "Bulgarian capital" , "seat of government" , "Foreign city" , "Capital of Bulgaria" , "Bulgarian city" .)