One breaks new organ playing Grieg? (9)
I believe the answer is:
norwegian
'grieg?' is the definition.
(composer Edvard Grieg is an example)
'one breaks new organ playing' is the wordplay.
'one' becomes 'i' (Roman numeral).
'breaks' is an insertion indicator.
'playing' is an anagram indicator.
'new'+'organ'='neworgan'
'neworgan' with letters rearranged gives 'norwegan'.
'i' put inside 'norwegan' is 'NORWEGIAN'.
(Other definitions for norwegian that I've seen before include "like King Harald I" , "1 in 21 [OSLO] possibly" , "Native of Bergen, say" , "Northerner" , "Native to, eg, Oslo" .)