Mountain in an African country (5)
I believe the answer is:
benin
'an african country' is the definition.
(country in Africa)
'mountain in' is the wordplay.
'mountain' becomes 'ben' (ben is a kind of mountain).
'ben'+'in'='BENIN'
(Other definitions for benin that I've seen before include "Nation" , "West African country, formerly French colony of Dahomey" , "Old West African kingdom from which 'bronze' sculptures were looted by the British in 1897" , "French-speaking West African country" , "West African republic" .)