With 87-Down, idiom about wasting one's efforts ... as seen in four columns in this puzzle?

PEARLSBEFORE

Think of a phrase warning against offering something valuable to those who won’t appreciate it—this answer is the first half of that saying.

This clue hints at the idiom "casting pearls before swine," which means wasting valuable things on people who won’t appreciate them. The answer is split across two parts—this entry ("PEARLSBEFORE") and 87-Down (likely "SWINE")—to complete the phrase. The clue also playfully notes that the letters of "PEARLS" appear in four separate vertical columns elsewhere in the puzzle, reinforcing the theme of scattered or wasted effort. It’s a clever way to tie the idiom’s meaning to the puzzle’s structure.