Rescue original piece of valuable silver found in auction (7)
I believe the answer is:
salvage
'rescue' is the definition.
(salvage is a kind of rescue)
'original piece of valuable silver found in auction' is the wordplay.
'original piece of' says to take the initial letters.
'silver' becomes 'ag' (Ag is the chemical symbol for silver).
'found in' means one lot of letters goes inside another.
'auction' becomes 'sale' (I've seen this before).
The first letter of 'valuable' is 'v'.
'v'+'ag'='vag'
'vag' put within 'sale' is 'SALVAGE'.
(Other definitions for salvage that I've seen before include "Recovery of wrecks" , "Rescue of property as from fire or flood" , "Retrieve goods from wrecked ship" , "Collect discarded material" , "Rescue (and recycle?)" .)