Finished carriage is masterful (11)
I believe the answer is:
overbearing
'masterful' is the definition.
(thesaurus)
'finished carriage' is the wordplay.
'finished' becomes 'over' (similar in meaning).
'carriage' becomes 'bearing' (synonyms).
'over'+'bearing'='OVERBEARING'
'is' is the link.
(Other definitions for overbearing that I've seen before include "Officious" , "Forceful in character" , "Unpleasantly dominating" , "High-handed" , "Arrogant" .)