Inventor is done working (6)
I believe the answer is:
edison
'inventor' is the definition.
(Edison is an example)
'is done working' is the wordplay.
'working' is an anagram indicator.
'is'+'done'='isdone'
'isdone' with letters rearranged gives 'EDISON'.
(Other definitions for edison that I've seen before include "Inventor's" , "Inventor of the carbon filament lamp, d. 1931" , "Onside with great American inventor" , "Thomas --, US?inventor" , "Thomas Alva ......, great American inventor" .)