It bites

GATOR

["This reptile with a powerful jaw is often found lurking in southern swamps or rivers, and its name is short for a much larger creature."]

The clue "It bites" is a playful hint at "GATOR," short for alligator—a creature known for its powerful bite. The word "bites" directly ties to the animal’s behavior, making it a straightforward but clever reference. It’s a common crossword trick to use shortened or informal terms like "gator" instead of the full word.