Bluish-white metal (4)
I believe the answer is:
zinc
'bluish-white metal' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for zinc that I've seen before include "Metallic element present with copper in brass" , "Metal alloyed with copper to make brass" , "White metallic element, symbol Zn" , "Type of metal" , "Anti-corrosion agent" .)