Signal to Evacuate a Building
Puzzle 4 of Brad Pitt Easy Pack
Question is: Signal to Evacuate a Building
and the answer is: FIREALARM
Word Meaning:
FIRE ALARM — An electromechanical or electronic bell, klaxon, chime, horn, speaker, strobe light or other device which warns people in a building etc. of a possible fire or other condition requiring evacuation.
Definitions from Wiktionary.