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All answers having "Leavening agent" as clue:

4 Character Answers:

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SODA



5 Character Answers:

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ABOVO

AORTA

DOUBT

ESSAY

EXACT

YEAST



10 Character Answers:

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BAKINGSODA



12 Character Answers:

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INTERMEDIATE

RAINBOWTROUT



13 Character Answers:

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SITTINGPRETTY