### Clue: Starting with impenetrable vacant stare, reported appearance of US Mafiosi (4-4)
### Answer: WISE-GUYS 
 ### Explanation: Definition: US Mafiosi
A charade of WI ('starting **W**ith **I**mpenetrable') plus SE ('vacant **S**tar**E**') plus GUYS, sounding like ('reported') GUISE ('appearance').