Everybody in Wall Street
I believe the answer is:
all
'everybody' is the definition.
(I've seen this in another clue)
'in wall street' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ALL' can be found hidden inside 'wall street'.
(Other definitions for all that I've seen before include "The lot, everyone" , "Total" , "SECOND PART OF 8" , "and 18: 'Sing through -- --' (carol)" , "nothing more" .)