The most common and most likely answer to this crossword clue is the 5 letter word LOUIS
I've seen this crossword clue in The Guardian
L
O
U
I
S
More clues leading to the result LOUIS
- Boxer Rebellion's central character succeeded after French agreement
- Blériot’s gold coin?
- King in line? Yes in Paris followed by son
- French monarch‘s solution? Fighting not fleeing
- Prize fighter once given old gold coin
- Former king left agreement in France
- Zero oil initially used up, acquiring thrust in continental style
- Our solid change, just one old coin
Buddy explains!

The straight part
We know that "gold coin/gold coin" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gold coin/gold coin = louis.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 LOUIS mean?
LOUIS noun- Any gold or silver coin issued by the French kings from Louis XIII to Louis XVI and bearing their image on the obverse side, particularly the gold louis d'ors, originally a French form of the Spanish doubloon but varying in value between 10 and 24 livres.
- The louis d'or constitutionnel, a 24-livre gold coin issued by the First French Republic.
- The franc germinal or napoleon, a similar gold coin issued by Napoleon and bearing his image on the obverse, worth 20 francs.