Accomplished, competent (4)
I believe the answer is:
able
This clue is a double definition.
'accomplished' is the first definition.
(I've seen this in another clue)
'competent' is the second definition.
(similar in meaning)
(Other definitions for able that I've seen before include "Fully competent" , "Capable seaman" , "As capable as a mariner" , "Adept" , "showing talent" .)