Country with troubled reign (5)
I believe the answer is:
niger
'country' is the definition.
(African country)
'troubled reign' is the wordplay.
'troubled' indicates anagramming the letters.
'reign' anagrammed gives 'NIGER'.
'with' acts as a link.
(Other definitions for niger that I've seen before include "African river flowing into the South Atlantic" , "West African republic" , "Landlocked W African republic" , "W. African country" , "River, Africa's largest delta" .)