A key adviser in an Australian city (8)
I believe the answer is:
adelaide
'an australian city' is the definition.
(I've seen this before)
'a key adviser' is the wordplay.
'key' becomes 'del' (del key on a keyboard).
'adviser' becomes 'aide'.
'a'+'del'+'aide'='ADELAIDE'
'in' acts as a link.
(Other definitions for adelaide that I've seen before include "South Australia's capital" , "Queen < in opera" , "port in Oz" , "State capital of South Australia" , "Lead aide to Oz" .)