Backbiter?

FLEA

This tiny bloodsucker might leave you scratching, but it’s not known for spreading gossip—just irritation.

"Backbiter" hints at something that bites from behind, which a flea literally does—it’s a tiny insect that jumps onto hosts and bites their skin. The question mark signals wordplay, suggesting the answer isn’t a literal gossip (another meaning of "backbiter") but a playful twist on the idea. Fleas are notorious for their sneaky, irritating bites, making them a clever fit for the clue.