Is it ensure, insure, or assure?
"leader of a Mafia 'family,' " 1952, Italian, literally "head" (see head (n.)).
"pitch-altering device for a stringed instrument," 1946, short for capo tasto (1876), from Italian, literally "head stop" (see head (n.)).
The head of a local unit of the Mafia; Mafia captain: identified as Mafia capo by whatever's current crime commission
[fr Italian, ''head, chief'']