Precious metal for a blonde (8)
I believe the answer is:
platinum
I believe this clue is a double definition.
'precious metal' is the first definition.
(I've seen this before)
'a blonde' is the second definition.
(I've seen this before)
'for' is the link.
(Other definitions for platinum that I've seen before include "Valuable substance" , "Precious silvery-white metal" , "Type of blonde; best-selling (record)" , "Jewellers' metal" , "Atomic number 78" .)