The most common and most likely answer to this crossword clue is the 10 letter word TOURNIQUET
I've seen this crossword clue in The Guardian
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More clues leading to the result TOURNIQUET
- Device that prevents pouring out of claret
- Quite badly injured on journey north – need this?
- Winding round quite tightly, primarily restricting vessel with this?
- One’ll restrict flow of claret to jug when getting quite drunk
- Our quintet needs arrangement for one instrument
- When it’s around the claret’s kept out of sight
- Another bloody hold-up!
- Become quite agitated when grasping middle of boa constrictor
Buddy explains!

The straight part
We know that "Device that prevents pouring out of claret" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case device that prevents pouring out of claret = tourniquet.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 TOURNIQUET mean?
TOURNIQUET noun- A tightly-compressed bandage used to stop bleeding by stopping the flow of blood through a large artery in a limb.
- Any of several similar methods of clamping components into position.
- A turnstile.