Reign disrupted in African republic (5)
I believe the answer is:
niger
'african republic' is the definition.
(African country)
'reign disrupted' is the wordplay.
'disrupted' is an anagram indicator.
'reign' anagrammed gives 'NIGER'.
'in' is the link.
(Other definitions for niger that I've seen before include "Land-locked country and river of W Africa" , "Part of Africa" , "foreign banker" , "W. African country" , "Landlocked W African republic" .)