Mascara mishap

SMEAR

["Think about what often happens when applying this eyelash darkener goes awry."]

The clue "Mascara mishap" leads to the answer "SMEAR" through a straightforward definition. A mishap with mascara, a cosmetic used to darken and enhance eyelashes, often results in a smear, which is a streak or blob of the makeup spread or smudged unintentionally. The clue directly defines the answer without any puns or complex wordplay, relying on the common experience of a mascara mishap resulting in a smear.