Practical arrangement of Haydn (5)
I believe the answer is:
handy
'practical' is the definition.
(thesaurus)
'arrangement of haydn' is the wordplay.
'arrangement of' indicates anagramming the letters.
'haydn' with letters rearranged gives 'HANDY'.
(Other definitions for handy that I've seen before include "Useful - competent" , "Convenient; skilful" , "Close by" , "Accessible" , "Useful and convenient" .)