A way to gain admission (6)
I believe the answer is:
access
I believe this clue is a double definition.
'a way to gain' is the first definition.
(I know that access is a more specific form of the action arrive at)
'admission' is the second definition.
(I've seen this before)
(Other definitions for access that I've seen before include "Means, or right, of approach" , "Admittance, entree" , "Way of entering or leaving" , "drive, perhaps" , "Right or way to enter" .)