First man's Australian, flipping furious (4)
I believe the answer is:
adam
'first man's' is the definition.
(first man in the Bible)
'australian flipping furious' is the wordplay.
'australian' becomes 'A' (common abbreviation).
'flipping' says the letters should be written in reverse.
'furious' becomes 'mad' (I've seen this in other clues).
'mad' written backwards gives 'dam'.
'a'+'dam'='ADAM'
(Other definitions for adam that I've seen before include "First man in the Bible" , "__ Smith, author of The Wealth of Nations" , "Scottish architect, d.1792" , "father of us all?" , "First man of Genesis" .)