Doing business (4)
I believe the answer is:
open
'doing business' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for open that I've seen before include "Not closed or obstructed" , "Candid and undisguised" , "Not yet decided - to start" , "Contest that includes all comers" , "ready to entertain new ideas" .)