The most common and most likely answer to this crossword clue is the 10 letter word SANDBLASTS
S
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The straight part
We know that "Scours" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case scours = sandblasts.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 SANDBLASTS mean?
SANDBLASTS verb- To spray with fast-moving solid grains (such as sand propelled by compressed air, although softer material like sodium bicarbonate used for delicate materials may also be so referred to). The process is used for stripping dirt, rust, paint etc. from the surface of objects.