Musical works like this upset Old Nick (7)
I believe the answer is:
sonatas
'musical works' is the definition.
(sonata is a type of musical work)
'like this upset old nick' is the wordplay.
'like this' becomes 'so' ('like so').
'upset' shows that the letters should be reversed in order.
'old nick' becomes 'satan' (synonyms).
'satan' written backwards gives 'natas'.
'so'+'natas'='SONATAS'
(Other definitions for sonatas that I've seen before include "Piano pieces" , "Instrumental compositions" , "Classical pieces" , "musical items" , "10 [COMPOSITION]s" .)