Greek letter sent to South African city (4)
I believe the answer is:
pisa
'city' is the definition.
(Pisa is an example)
'greek letter sent to south african' is the wordplay.
'greek letter' becomes 'pi' (letter from the Greek alphabet**).
'sent to' is a charade indicator (letters next to each other).
'south african' becomes 'sa'.
'pi'+'sa'='PISA'
(Other definitions for pisa that I've seen before include "City on the River Arno" , "Italian city with famous tower" , "City in Tuscany" , "There's a marked inclination here" , "much-visited city" .)