Permission to enter (6)
(Other definitions for access that I've seen before include "Way of entering or leaving" , "Means or right of entry" , "Way in, means of approach" , "Means to enter a place" , "The right to use something or see someone" .)
(Other definitions for admittance that I've seen before include "Right to enter" , "Entry" , "Letting in" , "gives one the right to be there" , "What bouncer controls" .)