Jaw about the work of a composer (6)
I believe the answer is:
chopin
'a composer' is the definition.
(Frederic Chopin)
'jaw about the work' is the wordplay.
'jaw' becomes 'chin' (I have seen 'Lower jaw' mean 'chin' so perhaps 'jaw' could also mean 'chin').
'about' is an insertion indicator.
'the work' becomes 'op' (abbreviation for opus).
'chin' enclosing 'op' is 'CHOPIN'.
'of' is the link.
(Other definitions for chopin that I've seen before include "Frederic . . . . . ., great 19th century Polish composer" , "Polish composer of much piano music" , "Polish composer who had affair with George Sand" , "Composer of "Tristesse"" , "his writing noted" .)