Related Clues:

• Hearing blood-sucking arachnid, it might be nervous
• Idiosyncratic behavior
• Twitch at odd points?
• Nervous symptom
• Facial twitch, say
• Rapid blinking, for one
• ___ Tac (mint)
• Start of X-X-X
• Quirk of brief noise made by a clock
• Classic game opener
• Twitch, spasm
• First of three O's