Clue mixed with open abundance (8)
I believe the answer is:
opulence
'abundance' is the definition.
(I've seen this in another clue)
'clue mixed with open' is the wordplay.
'mixed with' is an anagram indicator.
'clue' anagrammed with 'open' can make 'OPULENCE'.
(Other definitions for opulence that I've seen before include "Rich quality" , "wealth is manifest" , "Fortune" , "Great wealth" , "Open clue? (anag)" .)