Metal for the van (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)
'the van' is the second definition.
(van can mean the front of something)
'for' is the link.
(Other definitions for lead that I've seen before include "Heavy malleable metallic element" , "Command; metal" , "Guide by going in front" , "Leash -- Pb" , "Travel in front of" .)