Crossword puzzle clue "athletic infraction or what occurs at the beginning of this puzzle's four theme answers both across and down"

Athletic infraction ... or what occurs at the beginning of this puzzle's four theme answers, both across and down

Metaphor for time ... and, when divided into three words, puzzle theme found in the four longest across answers

Chemical reaction phenomenon, and what occurs in four symmetrical pairs of long answers in this puzzle

Athletic boost "taken" by the four theme answers

Swing both ways, and a literal hint to how four puzzle answers were created

Number of times this puzzle's theme word appears diagonally in the grid (to complete the puzzle, shade those words plus the Down answers that begin where they meet)

Feature of a windswept desert, and of this puzzle's four longest Across answers

"Home work" letters that appear at both ends of this puzzle's theme answers