Tragedy elevated Sid and Nancy? So it's said (8)
I believe the answer is:
disaster
'tragedy' is the definition.
('disaster' can be a synonym of 'tragedy')
'elevated sid and nancy? so it's said' is the wordplay.
'elevated' says the letters should be written in reverse.
'and' means one lot of letters go next to another.
'nancy?' becomes 'astor' (Nancy Astor).
'so it's said' indicates a 'sounds like' (homophone) clue.
'astor' sounds like 'aster'.
'sid' back-to-front is 'dis'.
'dis'+'aster'='DISASTER'
(Other definitions for disaster that I've seen before include "Terrible calamity" , "Great tradegy or cataclysm" , "Heavy blow" , "Catastrophic occurrence" , "not a success!" .)