The most common and most likely answer to this crossword clue is the 6 letter word PIERRE
I've seen this crossword clue in The Guardian
P
I
E
R
R
E
More clues leading to the result PIERRE
- Frenchman landing place with royal backing
- A Frenchman, often I wander in Peru
- French revolutionary losing clothes in US capital
- The Rock of Marseille in connection with south of quay
- French lad with clothes taken from French revolutionary
- 18 boy and bird wander in
- Mistake admitted by holy English fellow in France?
Buddy explains!
The straight part
We know that "The Rock of Marseille" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the rock of marseille = pierre.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.