This writer’s friend, a jumpy African native (6)
I believe the answer is:
impala
'jumpy african native' is the definition.
(I know that impala are native to Africa)
'this writer's friend a' is the wordplay.
'this writer's' becomes 'I'm' (the person writing the crossword clues).
'friend' becomes 'pal' (pal can mean a friend).
'im'+'pal'+'a'='IMPALA'
(Other definitions for impala that I've seen before include "horned beast" , "runner and long jumper from Africa" , "Species of African antelope" , "horny creature" , "Spectacular jumper" .)