Species of antelopes round the capital of Ethiopia (5)
I believe the answer is:
genus
'species' is the definition.
(thesaurus)
'antelopes round the capital of ethiopia' is the wordplay.
'antelopes' becomes 'gnus' (gnu is a kind of antelope).
'round' indicates putting letters inside.
'the capital of' suggests taking the first letters.
The initial letter of 'ethiopia' is 'e'.
'gnus' placed around 'e' is 'GENUS'.
'of' acts as a link.
(Other definitions for genus that I've seen before include "Part of the family" , "Taxonomic class between family and species" , "Category above species (Biology)" , "Category between family and species" , "The Homo of Homo sapiens?" .)