Related Clues:

• Enthusiastic, as an attitude
• Unfailing
• Free from doubt
• 'That'd be fine'
• 'Why not?!'
• 'You got it'
• Doubtless
• 'No prob'
• "Without a doubt!"
• Ready for any challenge
• "Why not?"
• "Absolutely!"
• Absolutely certain
• "Of course!"
• Fully convinced