The most common and most likely answer to this crossword clue is the 6 letter word SCOTCH
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More clues leading to the result SCOTCH
Buddy explains!

The straight part
We know that "Put an end to/whisky" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case put an end to/whisky = scotch.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 SCOTCH mean?
SCOTCH noun- A surface cut or abrasion.
- A line drawn on the ground, as one used in playing hopscotch.
- A block for a wheel or other round object; a chock, wedge, prop, or other support, to prevent slipping.
- To cut or score; to wound superficially.
- To prevent (something) from being successful.
- To debunk or discredit an idea or rumor.
- To block a wheel or other round object.
- To dress (stone) with a pick or pointed instrument.
- To beat yarn in order to break up slugs and align the threads.
- To clothe or cover up.
- (as a plural noun, the Scotch) The people of Scotland.
- Whisky distilled in Scotland, especially from malted barley.
- Any variety of Scotch.
- A glass of Scotch.
- Of or from Scotland; Scottish.
- Scotch tape
- (Australian rhyming slang) To rape.