Bluish-white metallic element (4)
I believe the answer is:
zinc
'bluish-white metallic element' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for zinc that I've seen before include "Metal much used in alloys" , "trace element" , "Type of metal" , "coat for protection" , "White metallic element used in alloys" .)