Ancestor's wifeless worker at seam? (5)

I believe the answer is:

elder

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'ancestor's' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for elder that I've seen before include "Senior - presbyter" , "Small tree with purple berries" , "Senior tribal figure" , "Tree for a church senior" , "Senior type of tree?" .)

I've seen this clue in The Sun.

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