Crossword Genius

Nine-headed serpent Hercules slew (5)

Ross

I believe the answer is:

hydra

(Other definitions for hydra that I've seen before include "Proliferating-head monster" , "Many-headed serpent" , "Many-headed snake slain by Hercules" , "that regenerated after cuts at the top" , "Many-headed monster of Greek mythology" .)

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