Heavy metal item damaged -- wait for delivery (4,4)
I believe the answer is:
lead time
'wait for delivery' is the definition.
(I've seen this before)
'heavy metal item damaged' is the wordplay.
'heavy metal' becomes 'lead' (lead is a heavy metal).
'damaged' indicates anagramming the letters.
'item' anagrammed gives 'time'.
'lead'+'time'='LEAD TIME'
(Other definitions for lead time that I've seen before include "Interval between the initiation and the completion of a process" , "Interval between the start and completion of a production process" , "I'm elated over advance period before start" , "delay" , "Period between start and finish of production process" .)