Expert — achieved (12)
I believe the answer is:
accomplished
I believe this clue is a double definition.
'expert' is the first definition.
(synonyms)
'achieved' is the second definition.
('accomplish' can be a synonym of 'achieve')
(Other definitions for accomplished that I've seen before include "Talented - performed" , "executed" , "Highly skilled" , "Consummate" , "Having particular skills" .)