Overdone ham (10)
I believe the answer is:
theatrical
I believe this clue is a double definition.
'overdone' is the first definition.
(thesaurus)
'ham' is the second definition.
(ham or hammy can mean overly theatrical acting)
(Other definitions for theatrical that I've seen before include "Artificial and exaggerated" , "Actor" , "Relating to acting/actors" , "Showbiz" , "overdramatic" .)