Conduct Beethoven's Fifth, with a bouvier barking (9)
I believe the answer is:
behaviour
'conduct' is the definition.
('behaviour' can be a synonym of 'conduct')
'beethoven's fifth with a bouvier barking' is the wordplay.
'beethoven's fifth' becomes 'h' (I've seen this in other clues).
'with' says to put letters next to each other.
'barking' indicates anagramming the letters (UK slang for mad).
'a'+'bouvier'='abouvier'
'h' put after 'abouvier' is 'abouvierh'.
'abouvierh' with letters rearranged gives 'BEHAVIOUR'.
(Other definitions for behaviour that I've seen before include "Bearing" , "Conduct - performance" , "Conduct, demeanour" , "Comportment" , "Personal conduct" .)