Sue is a funny person from down under (6)
I believe the answer is:
aussie
'person from down under' is the definition.
(I've seen this in another clue)
'sue is a funny' is the wordplay.
'funny' indicates an anagram.
'sue'+'is'+'a'='sueisa'
'sueisa' is an anagram of 'AUSSIE'.
(Other definitions for aussie that I've seen before include "Native of Canberra (colloq.)" , "Australian (colloq.)" , "Someone from Sydney? (slang)" , "Someone from Melbourne, perhaps (slang)" , "Antipodean native, informally" .)