Answer:

alerting

Answer	Crossword Clue
ALERTING	Putting on guard
ALERTING	Siren's function
ALERTING	Emulating Paul Revere

ALERTING	Paul Revere's midnight duty
ALERTING	Red flag's purpose
ALERTING	Tipping off
ALERTING	Sounding the alarm

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.