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All answers having "Vents" as clue:

4 Character Answers:

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AIRS



5 Character Answers:

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FLUES



6 Character Answers:

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ERUPTS



7 Character Answers:

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AIRWAYS

CAPITAL

LOUVERS

OUTAGES

OUTLETS

UNLOADS



8 Character Answers:

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AIRHOLES



9 Character Answers:

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UNLEASHES