Ctrl-___-Del

ALT

This key often works with Ctrl for shortcuts like switching windows or accessing menus in many programs.

This clue references the classic keyboard shortcut "Ctrl-Alt-Del," often used to reboot a computer or open the task manager. The blank represents the missing key in the sequence, which is "Alt." It’s a straightforward fill-in-the-blank based on a well-known tech command, so no wordplay—just recognizing the familiar key combination.