March saving lives for Heaven (8)
I believe the answer is:
paradise
'heaven' is the definition.
(synonyms)
'march saving lives' is the wordplay.
'march' becomes 'parade' (synonyms).
'saving' means one lot of letters goes inside another.
'lives' becomes 'is' ('be' can be a synonym of 'live').
'parade' placed around 'is' is 'PARADISE'.
'for' is the link.
(Other definitions for paradise that I've seen before include "blissful place?" , "Felicity" , "a state of bliss" , "Place of utter bliss" , "Garden of Eden" .)