Saves primitives left inside (8)
I believe the answer is:
salvages
'saves' is the definition.
('salvage' can be a synonym of 'save')
'primitives left inside' is the wordplay.
'primitives' becomes 'savages' (savage is a kind of primitive).
'left' becomes 'l' (common abbreviation).
'inside' means one lot of letters goes inside another.
'savages' enclosing 'l' is 'SALVAGES'.
(Other definitions for salvages that I've seen before include "Rescues" , "Saves discarded material" , "dry Eliot piece" , "Saves from fire in Las Vegas" .)