Dungeon’s new arrangement of Let It Be after endless tour (9)
I believe the answer is:
oubliette
'dungeon's' is the definition.
(oubliette is a kind of dungeon)
'new arrangement of let it be after endless tour' is the wordplay.
'new arrangement of' indicates anagramming the letters.
'after' is a charade indicator (letters next to each other).
'endless' says to take the centre.
The middle of 'tour' is 'ou'.
'let'+'it'+'be'='letitbe'
'letitbe' anagrammed gives 'bliette'.
'bliette' after 'ou' is 'OUBLIETTE'.
(Another definition for oubliette that I've seen is " Trapdoor-accessed dungeon".)