The most common and most likely answer to this crossword clue is the 8 letter word MONROVIA
I've seen this crossword clue in Financial Times
M
O
N
R
O
V
I
A
More clues leading to the result MONROVIA
Buddy explains!

The straight part
We know that "African capital" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case african capital = monrovia.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.