Possible Clues:

• Writer not returning to walled city
• Novelist who created Father Brown
• Writer's item for storing college files foremost in room
• Remote don dared attack Belloc's
• Writer using part of body toner, exercising
• From another sect, not a deficient writer
• Box clever in the end, entering school as writer
• Writer from walled city to north
• G.K. —, English author
• Poet and novelist whose father was a detective