Scoundrel in Canberra regularly repeated mumbo-jumbo (11)
I believe the answer is:
abracadabra
'mumbo-jumbo' is the definition.
(thesaurus)
'scoundrel in canberra regularly repeated' is the wordplay.
'scoundrel' becomes 'cad' (cad is a kind of scoundrel).
'in' means one lot of letters goes inside another.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'repeated' shows that letters should be duplicated.
The alternating letters of 'canberra' are 'abra'.
'abra' duplicated is 'abraabra'.
'cad' put within 'abraabra' is 'ABRACADABRA'.
(Other definitions for abracadabra that I've seen before include "for a spell it is declared" , "Magic word used by conjurors" , "Magic word - gibberish!" , "Word used by conjuror" , "Word said to trick" .)