The most common and most likely answer to this crossword clue is the 9 letter word WHITEWASH
I've seen this crossword clue in The Daily Telegraph
W
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More clues leading to the result WHITEWASH
Buddy explains!
The straight part
We know that "Cover up/heavy defeat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cover up/heavy defeat = whitewash.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 WHITEWASH mean?
WHITEWASH noun- A lime and water mixture for painting walls and fences bright white.
- A complete victory or series of victories without suffering any losses; a clean sweep.
- Any liquid composition for whitening something, such as a wash for making the skin fair.
- A campaign to paper over unfavorable elements.
- To paint over with a lime and water mixture so as to brighten up a wall or fence.
- To cover over errors or bad actions.
- To repay the financial debts of (another person).
- (late, 19th century) To prevent a team from scoring any runs.
- In various games, to defeat (an opponent) so that they fail to score, or to reach a certain point in the game; to skunk.
- To make over (a person or character, a group, an event, etc) so that it is or seems more white, for example by applying makeup to a person, or by covering over the participation of people of color in an event and focusing on only white participation.