Possible Clues:

• Rice dish recipe for starters — it's too complicated
• A knight is back for food, to it to and fro
• Dish motorist did not start cooking
• Riot about the sot for such a dish
• Rude sort: one to scoff
• Back the knight to go to and fro in such a stew
• The knight turns up with 15 across for something to eat
• The knight goes up and to and fro as a matter of course
• The knight goes back and to and fro for food
• Its root may be made into a stew