The most common and most likely answer to this crossword clue is the 9 letter word WATERMARK
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Buddy explains!
The straight part
We know that "Distinct impression" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case distinct impression = watermark.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 WATERMARK mean?
WATERMARK noun- A translucent design impressed on the surface of paper and visible when the paper is held to the light.
- (by extension) A logo superimposed on a digital image, a television broadcast, etc.
- A value stored in a datafile to ensure its integrity, so that if the file's contents are changed then the watermark will no longer match the contents.
- A mark indicating the level to which water has risen.
- To mark paper with a watermark.
- To mark a datafile with a digital watermark.