Possible Clues:

• With 41-Across, kidnapper's correspondence
• Romans required money to get free
• Are, in short, with moans at having to pay it
• How demanding the son becomes with the 20 down around!
• Very large amount if it's for royalty children's author reported
• Managed like this the thousand that's demanded
• Transparency; move smoothly
• Managed a few, by the sound of it, for what is demanded (6).
• Freedom payment
• Payment, eg to kidnapper