Tony --, Australian prime minister from 2013 to 2015 (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
abbott
(Other definitions for abbott that I've seen before include "one of a comic duo" , "Bud ... and Lou Costello" , "Costello's comedy partner" , "Costello's film partner" , "Double act partner of Lou Costello" .)