Related Clues:
- One down in the dumps?
- Certain stowaway
- Turn state's evidence, maybe
- Small mouselike rodent
- One who squeals
- "Was it a ___?" "Yeah, a great big one" (line from "L.A. Confidential")
- Slum scurrier
- Mafioso informer
- Vole relative
- Pack __
- ___ Pack (Sinatra and pals)
- Inform (on)
- Urban vermin
- Chinese calendar animal ... or the key to this puzzle's theme
- Subway station critter