It really depends on what the client wants it for... There are legitimate companies that have "mafia" in their name, for example in Finland (My country of birth) there was a legitimate radio station called "Radio Mafia".
Well just on uspto.gov there are 112 registered trademarks with the word Mafia in them.
But I had to giggle at how many are, well let's say, no longer.
Here is one of them:
Word Mark LA MAFIA
Serial Number 76203002
Owner (APPLICANT) La Mafia Enterprises Inc CORPORATION TEXAS 3232 Mainford Houston TEXAS 77009
Type of Mark TRADEMARK. SERVICE MARK
Register PRINCIPAL
Live/Dead Indicator DEAD
Word Mark LA MAFIA
Serial Number 76203002
Owner (APPLICANT) La Mafia Enterprises Inc CORPORATION TEXAS 3232 Mainford Houston TEXAS 77009
Type of Mark TRADEMARK. SERVICE MARK
Register PRINCIPAL
Live/Dead Indicator DEAD