Piece of scrap metal raised from sub
I believe the answer is:
temp
'sub' is the definition.
(I've seen this in another clue)
'piece of scrap metal raised' is the wordplay.
'piece of' indicates the answer is hidden within the clue.
'raised' is a reversal indicator (going up in a down clue).
'pmet' is hidden within 'scrap metal'.
'pmet' backwards is 'TEMP'.
'from' acts as a link.
(Other definitions for temp that I've seen before include "Non-permanent worker" , "Non-full time employee" , "Short-term office worker" , "Short-time worker" , "relief" .)