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.
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Question: Category: HEAVY MACHINERY 
Clue: By definition it's a machine that gives a surface an even degree of slope

Answer: grader


Question: Category: "GUN" SMOKE 
Clue: A bird dog may lose its job if it's this, afraid of loud noises

Answer: gun-shy


Question: Category: ANATOMY 
Clue: Like the one in the nose, this wall that divides the heart lengthwise can deviate

Answer:
the septum