Answer:
This is a dead giveaway
Take one royal word in the plural and make it singular by adding one letter
It can be cracked, It can be made, It can be told, it can be played. What is it?
White and thin, red within, with a nail at the end. What is it?
You fill it and it empties, A metaphor for plenty, Depending on what half you see, It's either full or empty
Two little holes in the side of a hill. Just as you come to the cherry-red mill.