Nan’s wild embraces much disturbed German composer (8)
I believe the answer is:
schumann
'german composer' is the definition.
(I've seen this before)
'nan's wild embraces much disturbed' is the wordplay.
'wild' indicates anagramming the letters.
'embraces' is an insertion indicator.
'disturbed' indicates anagramming the letters.
'nans' anagrammed gives 'sann'.
'much' is an anagram of 'chum'.
'sann' placed around 'chum' is 'SCHUMANN'.
(Other definitions for schumann that I've seen before include "Nan, chums go for this composer" , "German composer, 1810-56" , "Robert --, German romantic composer" , "German barman" , "Robert -, nineteenth century German composer" .)