Barbarian stifles lake rescue (7)
I believe the answer is:
Here is my best explanation:
'rescue' is the definition.
(salvage is a kind of rescue)
'barbarian stifles lake' is the wordplay.
'barbarian' becomes 'savage' ('savage' can be a synonym of 'barbarian').
'stifles' indicates putting letters inside.
'lake' becomes 'l'.
'savage' enclosing 'l' is 'salvage'.
(Other definitions for salvage that I've seen before include "Property that's rescued", "Reclaim", "recovery", "Restore", "Recovery of wrecks", "Cargo saved from wreck", "Rescue of a ship's cargo", "Rescue (and recycle?)", "Rescue (cargo) from wreck at sea" and "Save - junk".)