Follower of waste and want

NOT

Think of a small word that often pairs with "but" to express contrast or negation, especially in phrases about scarcity.

This clue plays on the phrase "waste not, want not," a common saying about avoiding waste to prevent scarcity. The words "waste" and "want" appear in the clue, and their "follower" is the word that comes after them in the phrase—"not." The answer is simply the last word in that well-known expression.