Endless farce exposed banal secrets (6)
I believe the answer is:
arcana
'secrets' is the definition.
(arcana are secrets or mysteries)
'endless farce exposed banal' is the wordplay.
'endless' indicates the central letters.
'exposed' indicates the central letters (the inside of the word is exposed).
The middle of 'farce' is 'arc'.
The central letters of 'banal' are 'ana'.
'arc'+'ana'='ARCANA'
(Other definitions for arcana that I've seen before include "Tarot cards" , "Secrets, mysteries" , "Secret things" .)