Middling grade

CEE

It’s the letter that sounds like the grade between B and D.

"Middling grade" is a play on the letter grade "C," which is often considered average or middle-of-the-road in grading systems. The answer "CEE" is simply the phonetic spelling of the letter "C," a common trick in crosswords where letters are clued by their names. It’s a straightforward example of how puzzles sometimes treat individual letters as words.