Eccentric Israeli composer (7)
I believe the answer is:
salieri
'composer' is the definition.
(Antonio Salieri)
'eccentric israeli' is the wordplay.
'eccentric' indicates an anagram.
'israeli' is an anagram of 'SALIERI'.
(Other definitions for salieri that I've seen before include "Rival of Mozart" , "Composer contemporary with Mozart" , "Italian composer" , "musician accused of murder" .)