Thus African country must be African! (6)
I believe the answer is:
somali
'african' is the definition.
(Somali is an example)
'thus african country' is the wordplay.
'thus' becomes 'so' (synonyms).
'african country' becomes 'mali' (country in Africa).
'so'+'mali'='SOMALI'
'must be' is the link.
(Other definitions for somali that I've seen before include "native language" , "East African national" , "African language" , "From a country in the Horn of Africa" , "1 [GCSE]" .)