Composer in German city not northern Australia (7)
I believe the answer is:
berlioz
'composer' is the definition.
(I've seen this before)
'german city not northern australia' is the wordplay.
'german city' becomes 'berlin' (Berlin is the capital of Germany).
'not' suggests deleting specific letters.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'australia' becomes 'oz' (informal name for Australia).
'berlin' with 'n' taken away is 'berli'.
'berli'+'oz'='BERLIOZ'
'in' is the link.
(Other definitions for berlioz that I've seen before include "Barman" , "One composer" , "Hector --, French composer" , "Composer of The Damnation of Faust, d. 1869" , "French composer,1803-69" .)