Australian and Yankee hosting finest PM (7)
I believe the answer is:
autopsy
'pm' is the definition.
(PM can mean postmortem)
'australian and yankee hosting finest' is the wordplay.
'australian' becomes 'aus' (common abbreviation).
'and' is a charade indicator (letters next to each other).
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'hosting' is an insertion indicator.
'finest' becomes 'top' (I've seen this before).
'aus'+'y'='ausy'
'ausy' enclosing 'top' is 'AUTOPSY'.
(Other definitions for autopsy that I've seen before include "final critical analysis" , "Examining body" , "Pays out (anag.)" , "A post-mortem examination of corpse" , "Examination to determine cause of death" .)