Metal to conduct (4)
I believe the answer is:
lead
I believe this clue is a double definition.
'metal' is the first definition.
(lead is a kind of metal)
'conduct' is the second definition.
(I've seen this before)
'to' is the link.
(Other definitions for lead that I've seen before include "Be ahead of - guide" , "Accompany to show the way" , "Chief performer" , "Guide, conduct" , "Leash -- Pb" .)