The most common and most likely answer to this crossword clue is the 9 letter word PLENITUDE
I've seen this crossword clue in Financial Times
P
L
E
N
I
T
U
D
E
Buddy explains!

The straight part
We know that "Wealth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wealth = plenitude.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does PLENITUDE mean?
PLENITUDE noun- Fullness; completeness.
- An abundance; a full supply.
- Fullness (of the moon).