Unusual feature of this puzzle … or, when parsed as two words (1,8), another unusual feature of this puzzle

ASYMMETRY

Consider how this grid might break the mirror test or describe its own uneven letter count.

This clue plays on the word "ASYMMETRY," which describes the puzzle’s irregular grid layout—something unusual in crosswords that typically have symmetrical designs. The second part hints at reading it as "A SYMMETRY," where "A" (one) plus "SYMMETRY" (eight letters) forms a punny twist: the puzzle lacks symmetry, making the answer fit both interpretations. The wordplay relies on splitting the answer into a number and a word, a common crossword trick to misdirect solvers.