Green’s Dictionary of Slang

1. (orig. US) the (usu. US) Mafia.

1967		L. Bruce Essential Lenny Bruce 76: It’s like two syndicates, man — the government syndicate, and the Maf.
1977		(con. 1969) M. Herr Dispatches 50: Spook deities, like Lou Conein [...] who (they said) ran it down the middle with the VC, the GVN, the Mission and the Corsican Maf.

2. attrib. use of sense 1.

1975

A. Goldman Lenny Bruce 19: Lenny can get bread [...] from the worst Maf types.