One rescuing volunteers eaten up by ’orrible savage (9)
I believe the answer is:
liberator
'one rescuing' is the definition.
'volunteers eaten up by 'orrible savage' is the wordplay.
I cannot really see how this works, but
'by' could be 'at' and 'at' is found within the answer.
This explanation may well be incorrect...
(Other definitions for liberator that I've seen before include "Daniel O'Connell is often referred to as one" , "he delivers" , "national hero" , "Freedom-fighter" , "One who sets people free" .)