How many letters does the top answer for “a person employed to keep watch for some anticipated event” have?

The most common answer is scout (5 letters).

Crossword clue: a person employed to keep watch for some anticipated event

3 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

scout 5 letters wn-def

explore, often with the goal of finding something or somebody

sentinel 8 letters wn-def

a person employed to keep watch for some anticipated event

sentry 6 letters wn-def

a person employed to keep watch for some anticipated event