“Once Upon a Mattress” prop Crossword Clue

 The answer to the crossword clue “Once Upon a Mattress” prop is PEA.

In the musical comedy Once Upon a Mattress, the princess must pass a test of sensitivity in order to marry Prince Dauntless. The test involves her sleeping on a mattress with twenty mattresses stacked on top of it. If she can't feel a single pea placed under the bottom mattress, she is considered to be a true princess.

In the end, the princess does pass the test, and she marries Prince Dauntless. The pea becomes a symbol of her true princesshood, and it is often used as a prop in productions of the musical.

Here is an example of how to use the word "pea" in a sentence:

The princess must sleep on twenty mattresses with a single pea placed under the bottom mattress in order to pass the test of sensitivity.

I hope this helps!