Possible Clues:

• French river (Orléans, Tours, Nantes)
• French banker with nothing to invest in former currency
• River, one at the heart of traditional teachings
• River passing through Oslo, I recall
• See earliest signs of Industrial Revolution near eastern part of France
• River that drains more than 20% of France
• The French king getting confused in his native river
• Oriel opens out on to French flower
• European river
• River one's found in legends