Element of the halogen group whose atomic number is 53 (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
iodine
(Other definitions for iodine that I've seen before include "Tincture for cuts" , "Hanging tuft" , "Element that can exist as a purple vapour" , "Black crystalline element" , "Mild antiseptic" .)