The most common and most likely answer to this crossword clue is the 5 letter word WONGA
I've seen this crossword clue in Financial Times
W
O
N
G
A
More clues leading to the result WONGA
- No good going in without answer ready
- Cash in silver, instantly withdrawn
- Silver currently making comeback, making dosh
- Incorrect answer teacher finally rejected twice? That's Aussie's pigeon!
- Taste of marshmallow on garlic bread
- Cash in silver immediately withdrawn
- Not right to cheat American out of money
- Money came first, introductions to grandees after
- Money earned, a third gained
- Stuff that can be made into a gown
Buddy explains!

The straight part
We know that "Cash" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cash = wonga.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 WONGA mean?
WONGA noun- Money.