Forgetfulness leads to our best violin being shattered (8)
I believe the answer is:
oblivion
'forgetfulness' is the definition.
(oblivion is a kind of forgetfulness)
'leads to our best violin being shattered' is the wordplay.
'leads to' says to take the initial letters.
'being shattered' indicates anagramming the letters.
The initial letters of 'our best' is 'ob'.
'violin' anagrammed gives 'livion'.
'ob'+'livion'='OBLIVION'
(Other definitions for oblivion that I've seen before include "Total forgetfulness -- limbo" , "lack of fame" , "State of being forgotten and disregarded" , "Last of man's 22 20 [SEVEN AGES]" , "Neglected state" .)