Baron (who's Australian); Dame (who wrote) (7)
I believe the answer is:
murdoch
'baron who's australian dame who wrote' is the definition.
The definition suggests a singular noun which matches the answer.
'who wrote' is the wordplay.
I cannot quite see how this works, but
'who' could be 'doc' and 'doc' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for murdoch that I've seen before include "Rupert --, media owner" , "Rupert --; Iris --" , "Press baron" , "Author of The Bell" , "Media mogul" .)