"Sure . . . why not!" (4)
(Other definitions for okay that I've seen before include "Authorise" , "Agree" , "All right; sanction" , "Give approval to" , "Not terrific but acceptable" .)
(Other definitions for lets that I've seen before include "we shall serve them again!" , "Yes" , "Rents out or allows" , "Leases" , "Allows or causes to" .)