The most common and most likely answer to this crossword clue is the 9 letter word UNDERWENT
I've seen this crossword clue in Independent
U
N
D
E
R
W
E
N
T
More clues leading to the result UNDERWENT
- Suffered in a French river
- Bore in a French river
- Experienced people keeping peace on river
- Did suffer going round in that new red number
- Bore beneath damp covering bottom of cabin
- Experienced peacekeepers by river
- Experienced, one over the Channel on lake
- Experienced university oarsman’s back on river
- Experienced a Parisian river
- Did bear run right off by river?
Buddy explains!

The straight part
We know that "Bore" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bore = underwent.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 UNDERWENT mean?
UNDERWENT verb- To go or move under or beneath.
- To experience; to pass through a phase.
- To suffer or endure; bear with.