Way to gain an admission (6)
I believe the answer is:
access
I believe this clue is a triple definition!
'way' is the first definition.
(I know that access is a type of way)
'to gain' is the second definition.
(accessing is a kind of gaining)
'an admission' is the third definition.
(I've seen this before)
(Other definitions for access that I've seen before include "The right to see, eg, children after divorce" , "Means of entry, passage" , "Means or right of entry" , "Right or way to enter" , "outburst" .)