African graduate's first class (5)
I believe the answer is:
masai
'african' is the definition.
(the Masai are an ethnic group of Kenya)
'graduate's first class' is the wordplay.
'graduate's' becomes 'MA's' (abbreviation for Master of Arts).
'first class' becomes 'ai' (A1 - top quality).
'mas'+'ai'='MASAI'
(Other definitions for masai that I've seen before include "Price increase" , "Highlander in Africa" , "East African native" , "East African people" , "People of the highlands of Kenya and Tanzania" .)