The most common and most likely answer to this crossword clue is the 8 letter word CONFLICT
I've seen this crossword clue in The Daily Telegraph
C
O
N
F
L
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C
T
More clues leading to the result CONFLICT
- Dispute working with Paris policeman in court
- Prisoner touched, it’s said, in dispute
- Struggle, seeing Tory beaten soundly by female
- Jailbird and French cop facing tense clash
- Dispute is about getting caught in leg slip
- Study to pass quickly without constant struggle
- Battle about playing, caught in move
- Fight with racket at the movie, Kelvin killed at last
- Battle against time keeps Nancy busy
Buddy explains!

The straight part
We know that "clash" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case clash = conflict.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 CONFLICT mean?
CONFLICT noun- A clash or disagreement, often violent, between two or more opposing groups or individuals.
- An incompatibility, as of two things that cannot be simultaneously fulfilled.
- To be at odds (with); to disagree or be incompatible
- To overlap (with), as in a schedule.