Unusual Elgar concert inspires international modern music producer (8,5)
I believe the answer is:
electric organ
'modern music producer' is the definition.
(modern musical instrument)
'unusual elgar concert inspires international' is the wordplay.
'unusual' is an anagram indicator.
'inspires' indicates putting letters inside (inspire means to breathe in).
'international' becomes 'i' (abbreviation eg in IMF).
'elgar'+'concert'='elgarconcert'
'elgarconcert' anagrammed gives 'electrcorgan'.
'electrcorgan' enclosing 'i' is 'ELECTRIC ORGAN'.
(Other definitions for electric organ that I've seen before include "Keyboard instrument" , "Synthesiser" .)