Accumulated knowledge or enlightenment (6)
I believe the answer is:
wisdom
I believe this is a double definition.
'accumulated knowledge' is the first definition.
(I've seen this in another clue)
'enlightenment' is the second definition.
(I've seen this before)
(Other definitions for wisdom that I've seen before include "See 13" , "Prudence - or Norman?" , "English actor, comedian and singer-songwriter (1915-2010)" , "Discernment" , "Accumulated experience and mature judgement" .)