The capital of South Australia (8)
I believe the answer is:
adelaide
'the capital of south australia' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for adelaide that I've seen before include "Australian city named for William IV's queen" , "19th century queen" , "South Australia's capital" , "Antipodean city" , "Lead aide out to Australia" .)