Uninvited guest

INTRUDER

This person might sneak in where they don’t belong, often causing alarm or disruption—think of someone breaking into a home or system.

"Uninvited guest" directly hints at someone who shows up where they’re not wanted. The answer "INTRUDER" fits perfectly because it describes a person who enters a place without permission, often causing disruption. There’s no hidden wordplay here—it’s a straightforward definition where the clue and answer match in meaning. Think of a burglar or someone sneaking into a party uninvited.