Not informed of such countless wealth? (6)
I believe the answer is:
untold
'such countless wealth?' is the definition.
(as in untold wealth)
'not informed' is the wordplay.
'not' becomes 'un' (prefix meaning 'not').
'informed' becomes 'told' (telling is a kind of informing).
'un'+'told'='UNTOLD'
'of' is the link.
(Other definitions for untold that I've seen before include "extensive" , "Lots" , "enormous" , "beyond description?" , "Unspoken - inexpressible - uncounted" .)