Wood sprite requiring gender re-assignment (3)

I believe the answer is:

elm

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'wood' is the definition.
(elm is a type of tree)

I don't understand the remainder of the clue.

(Other definitions for elm that I've seen before include "One [TYPE OF TREE]" , "Tall shade tree" , "I branch out" , "Hardwood tree" , "Tree of the genus Ulmus" .)

I've seen this clue in The Independent.

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