Punch Australia's opener after arsing about (7)
I believe the answer is:
sangria
'punch' is the definition.
(I've seen this before)
'australia's opener after arsing about' is the wordplay.
'opener' says to take the initial letters.
'after' says to put letters next to each other.
'about' indicates an anagram.
The initial letter of 'australias' is 'a'.
'arsing' is an anagram of 'sangri'.
'a' put after 'sangri' is 'SANGRIA'.
(Other definitions for sangria that I've seen before include "Spanish drink of red wine and spices" , "Spanish drink of wine, lemonade, fruit, etc" , "Red wine, fruit juice, sugar and spices" , "Spanish wine cocktail" , "Spanish wine/fruit drink" .)