Regularly admits shutdown a revelation (10)
I believe the answer is:
disclosure
'a revelation' is the definition.
('disclosure' can be a synonym of 'revelation')
'regularly admits shutdown' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'shutdown' becomes 'closure' (synonyms).
The alternate letters of 'admits' are 'dis'.
'dis'+'closure'='DISCLOSURE'
(Other definitions for disclosure that I've seen before include "broadcast" , "Laying bare" , "Release" , "revealing" , "Publication" .)