Performed by many a person (4)
I believe the answer is:
done
'performed' is the definition.
(done can mean performed or accomplished)
'by many a person' is the wordplay.
'by' is a charade indicator (letters next to each other).
'many' becomes 'D' (Roman numeral for 500).
'a person' becomes 'one' (an individual).
'd' put next to 'one' is 'DONE'.
(Other definitions for done that I've seen before include "Finished or ended" , "Finished like node" , "This sort of thing is socially acceptable" , "Performed" , "Thoroughly cooked; accomplished" .)