TASK DEFINITION: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
PROBLEM: Category: LEISURE ACTIVITIES 
Clue: In origami, folding paper down, away from you, is a mountain fold; folding it up toward you is this opposite

SOLUTION: a valley

PROBLEM: Category: SITCOM NEIGHBORS 
Clue: Nosy neighbor Gladys Kravitz

SOLUTION: bewitched

PROBLEM: Category: "OVER" & "UNDER" 
Clue: From the Old Norse for "having one's eyes closed", it's a serious mistake or oversight

SOLUTION:
a blunder