At Waterloo maybe nothing's lost after absolute end of Bonaparte (8)
I believe the answer is:
astatine
'at' is the definition.
('astatine' can be a synonym of 'at')
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for astatine that I've seen before include "radioactive material" , "Rare element" , "Atomic number 85" , "Chemical element At" , "Radioactive element" .)