Save a singer from massacre (3)
I believe the answer is:
but
'save' is the definition.
('but' can mean 'save' or 'except')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for but that I've seen before include "Only in attribution" , "On the contrary" , "Save" , "Only; apart from" , "However" .)