Christmas decoration dropped nail head in working men's toilet (9)

I believe the answer is:

mistletoe

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'christmas decoration' is the definition.
(Mistletoe is hung at Christmas)

I don't understand the rest of the clue.

(Other definitions for mistletoe that I've seen before include "Evergreen Christmas decoration" , "Parasitic plant" , "Stole mite from the Christmas plant" , "Something to stand under when kissing?" , "Kissed-under plant" .)

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

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