Answer: electriceye

AnswerCrossword Clue
ELECTRICEYESurveillance tool
ELECTRICEYEGarage door gadget
ELECTRICEYEAutomatic door device
ELECTRICEYEPhotocell
ELECTRICEYEDoor-controlling sensor
ELECTRICEYESensor of a sort
ELECTRICEYEMagic door opener.
ELECTRICEYEOne sensitive to light
ELECTRICEYESensor
ELECTRICEYEOne might set off an alarm