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' is an insertion indicator.
'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" .)