Related Clues:

• Showed anxiety
• Became rigid
• Tightened (up)
• Tightened
• Being so uptight, was in verbal fashion, perhaps
• Uptight in verbal form first
• Prepared to spring
• Grew rigid (with "up")
• Became anxious
• Became edgy
• Tightened up
• Got edgy
• Got nervous, with "up"
• Prepared for impact
• Prepared for a punch