A capital city, really African: just the tops? (5)
I believe the answer is:
accra
'a capital' is the definition.
(capital of Ghana)
'city really african just the tops?' is the wordplay.
'city' becomes 'acc' (I am not sure about this - if you are sure you should believe this answer much more).
'just the tops?' indicates taking the first letters.
The initial letters of 'really african' is 'ra'.
'acc'+'ra'='ACCRA'
(Other definitions for accra that I've seen before include "foreign capital" , "African port" , "Main city of Ghana" , "African city" , "Ghanaian capital" .)