Skilled arrangement of melodic chaps (12)
I believe the answer is:
accomplished
'skilled' is the definition.
('accomplished' can be similar in meaning to 'skilled')
'arrangement of melodic chaps' is the wordplay.
'arrangement of' indicates an anagram.
'melodic'+'chaps'='melodicchaps'
'melodicchaps' is an anagram of 'ACCOMPLISHED'.
(Other definitions for accomplished that I've seen before include "Talented - performed" , "Highly proficient" , "Highly skilled" , "Having particular skills" , "Completed; skilful" .)