Possible Clues:

• Opposite of a host
• Animal or plant that lives in or on another and is of no advantage to the host
• Sounds like the type of place you'd find British army regiment? The bloodsucker!
• Enlivening parties, a mistletoe sprig can be
• Tick two answers, about right, put in exercise
• Sponger gets a place by reversing charge
• It lives off its host
• Hanger-on?
• Tick or flea, e.g.
• What a host holds