Physicist is done working (6)
I believe the answer is:
edison
'physicist' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'is done working' is the wordplay.
'working' indicates an anagram.
'is'+'done'='isdone'
'isdone' with letters rearranged gives 'EDISON'.
Can you help me to learn more?
(Other definitions for edison that I've seen before include "US inventor of phonograph, electric light etc." , "Incandescent light inventor" , "No side to this american inventor" , "Inventor's" , "The inventor is strangely onside" .)