The most common and most likely answer to this crossword clue is the 7 letter word DETOURS
I've seen this crossword clue in The Guardian
D
E
T
O
U
R
S
Buddy explains!

The straight part
We know that "for Dutch force to French city (7)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case for dutch force to french city (7) = detours.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 DETOURS mean?
DETOURS noun- A diversion or deviation from one's original route.
- To make a detour.
- To direct or send on a detour.