Possible Clues:

• Dylan - - , poet
• A doubting ____
• Saint with doubts
• Wendy's pitchman, once
• He's a "really useful engine"
• and 22 Down: Theologian at home -- pi mask's blown apart!
• Musician Dolby who returned in 2011 with 'A Map of the Floating City'
• Male name
• One of the Twelve Apostles
• Inventive Edison