The most common and most likely answer to this crossword clue is the 11 letter word FRANCOPHONE
I've seen this crossword clue in The Guardian
F
R
A
N
C
O
P
H
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More clues leading to the result FRANCOPHONE
Buddy explains!
The straight part
We know that "de Gaulle, for one" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case de gaulle, for one = francophone.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.
Crossword Answer definitions
FRANCOPHONE noun- A person who speaks French, especially as their mother tongue.
- French-speaking.