How many letters does the top answer for “the act of detecting something; catching sight of something” have?

The most common answer is espial (6 letters).

Crossword clue: the act of detecting something; catching sight of something

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

espial 6 letters wn-def

the act of detecting something; catching sight of something

spotting 8 letters wn-def

the act of detecting something; catching sight of something

spying 6 letters wn-def

the act of detecting something; catching sight of something