adjective , adverb ( AustralE , NZE , informal )
1.
used to emphasize that sth is genuine or true, or to ask whether it is :
It's a fair dinkum Aussie wedding.
'Burt's just told me he's packing up in a month.' 'Fair dinkum?'
2.
used to emphasize that behaviour is acceptable :
They were asking a lot for the car, but fair dinkum considering how new it is.