Incredibly, punching “What is a stand over man?” in to Google proves fruitless.
A professional thug, usually. Somebody sent to “persuade” you.
Hmmm, could you be a little bit more specific?
TheLoadedDog is correct. In the Australian Macquarie Dictionary of slang, under “heavy”:
Cool. Thanks.
I presume you are talking about the late Jason Moran.
A stand over man collects money for protection or other rackets. “Lovely little cafe you have here in Lygon St, shame if anything broke.” Much of the action would be ripping off other crims for a portion of their blags, drug deals etc. Collection of payment on informal loans, gambling debts ect is often aided by threats of violence too.
But this:
What is a standover man?
would have worked.
In general, don’t search on Google using questions. Just search on words or phrases. If you search on “standover man,” you get this webpage:
http://www.wordreference.com/english/definition.asp?en=standover%20man
You also get a lot of hits with “stand over man.”
Which is exactly the same result that I got with my example. 