The most common and most likely answer to this crossword clue is the 10 letter word DISCOUNTED
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More clues leading to the result DISCOUNTED
Buddy explains!

The straight part
We know that "marked down" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case marked down = discounted.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 DISCOUNTED mean?
DISCOUNTED verb- To deduct from an account, debt, charge, and the like.
- To lend money upon, deducting the discount or allowance for interest
- To take into consideration beforehand; to anticipate and form conclusions concerning (an event).
- To leave out of account or regard as unimportant.
- To lend, or make a practice of lending, money, abating the discount
- (transactional analysis) To believe, or act as though one believes, that one's own feelings are more important than the reality of a situation.