Stupor leads to our best violin being ruined (8)
I believe the answer is:
oblivion
'stupor' is the definition.
(thesaurus)
'leads to our best violin being ruined' is the wordplay.
'leads to' says to take the initial letters.
'being ruined' is an anagram indicator.
The first letters of 'our best' is 'ob'.
'violin' is an anagram of 'livion'.
'ob'+'livion'='OBLIVION'
(Other definitions for oblivion that I've seen before include "State of being mentally withdrawn or blank" , "Total extinction" , "State of being forgotten and disregarded" , "State of being forgotten or unconscious" , "Unconsciousness - nothingness" .)