Beaten in AFL's playoffs (6)
I believe the answer is:
finals
'playoffs' is the definition.
(I've seen this in another clue)
'beaten in afl's' is the wordplay.
'beaten' is an anagram indicator (letters beaten up or destroyed).
'in'+'afls'='inafls'
'inafls' is an anagram of 'FINALS'.
(Other definitions for finals that I've seen before include "University exams" , "University examinations" , "Moral principles" , "Last exam at university" , "The last exams" .)