Study on leave in Africa (5)
I believe the answer is:
congo
'in africa' is the definition.
(I know that Congo is part of Africa)
'study on leave' is the wordplay.
'study' becomes 'con' (con can mean to study).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'leave' becomes 'go' (to go is to depart or leave).
'con'+'go'='CONGO'
(Other definitions for congo that I've seen before include "Former name of Zaire" , "Central African region" , "Central African country" , "Africa country and river" , "former African nation" .)