NYT Crossword Tips
Tip: Use ? for unknown answer letters, e.g. AN??ER. Use the space bar to enter ? quickly.

Clue: "Obstacle ... or any one of four black squares in this puzzle?"

"Obstacle ... or any one of four black squares in this puzzle?" is a New York Times crossword puzzle clue that we have seen 1 time.
Possible answer
Recent usage in crossword puzzles