Jumpers swear first Sunday to leap around extremes of tabernacle (8)

I believe the answer is:

sweaters

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But I can't explain it at all! Could you help me understand?

(Other definitions for sweaters that I've seen before include "Knitted upper garments" , "Jerseys, pullovers" , "Jumpers or pullovers - make you perspire" .)

I've seen this clue in the Sydney Morning Herald.

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