Related Clues:

• Unable to sit still
• Like a tie game in overtime
• Suspenseful
• Not easy
• All atwitter
• Under tension
• Future perfect, for one
• Pluperfect, e.g.
• Pulled tight
• Tight, as a drum skin
• Noun concerning verbs
• Needing a massage
• Tightly strung
• Not lax
• Slackless