Savage not to be trusted after a scalping? (8)
I believe the answer is:
ruthless
'savage' is the definition.
(thesaurus)
'not to be trusted after a scalping?' is the wordplay.
'not to be trusted' becomes 'truthless'.
'after a scalping?' means to remove the first letter.
'truthless' with its initial letter taken off is 'RUTHLESS'.
(Other definitions for ruthless that I've seen before include "Showing no compassion" , "Brutal" , "Lacking pity or mercy" , "Showing no mercy" , "Without pity, merciless" .)