Difficult and tiring with right pair in Australia (7)
I believe the answer is:
arduous
'difficult and tiring' is the definition.
(arduous means hard)
'right pair in australia' is the wordplay.
'right' becomes 'r' (common abbreviation).
'pair' becomes 'duo' (two people).
'in' indicates putting letters inside.
'australia' becomes 'Aus' (abbreviation).
'r'+'duo'='rduo'
'rduo' placed into 'aus' is 'ARDUOUS'.
'with' acts as a link.
(Other definitions for arduous that I've seen before include "Punishing" , "Burdensome" , "Requiring hard work" , "Daunting: strenuous" , "Extremely taxing" .)