Girl’s a new doctor in South Africa (6)
I believe the answer is:
sandra
'girl's' is the definition.
'a new doctor in south africa' is the wordplay.
'a new' becomes 'an' (I've seen this in other clues).
'doctor' becomes 'dr' (synonyms).
'in' indicates putting letters inside.
'south africa' becomes 'sa' (abbreviation).
'an'+'dr'='andr'
'andr' placed into 'sa' is 'SANDRA'.
(Other definitions for sandra that I've seen before include "woman's name" , "girl" , "So woman" , "Girl's name" .)