Gnu.
A three letter African antelope is the "gnu", which ends in a "u" not a "you". The more common name for the gnu is the wildebeeste, but that won't fit into your crossword puzzle.
Suni
Ibex
gnu
Sable antelope and springbok are antelope species in Africa.
That would be the largest of the African antelope, the Eland.
Yellow-backed Duiker is an antelope species in Africa.
Dorcan Gazelle
Gnu is a three letter word for an African antelope
dik dik
· Nyala
Another name for a South African antelope starting with the letter "G" is a gazelle. A gnu is also considered an ancestor of the antelope.