In the pun, the word "field" is being used for its multiple meanings.
The word "field" is being used for its multiple meanings in the pun, "The scarecrow won an award because he was outstanding in his field." The pun plays on the literal meaning of "field," which refers to the scarecrow being excellent at his job of guarding the field. At the same time, the pun also plays on the figurative meaning of "field," which refers to a particular area of expertise or profession. So, the word "field" in this pun has multiple meanings, making it the answer to the question.
