The most common and most likely answer to this crossword clue is the 8 letter word GUILDERS
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Buddy explains!
The straight part
We know that "old money" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old money = guilders.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 GUILDERS mean?
GUILDERS noun- One who gilds; especially one whose occupation is to overlay things with gold.
- The former currency unit in the Netherlands, divided into 100 cents.
- The former currency unit in Suriname, divided into 100 cents.
- The current currency unit in the islands in the former Netherlands Antilles, divided into 100 cents.