The most common and most likely answer to this crossword clue is the 10 letter word OVERLAYING
I've seen this crossword clue in Independent
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Buddy explains!
The straight part
We know that "Covering up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case covering up = overlaying.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 OVERLAYING mean?
OVERLAYING verb- To lay, spread, or apply something over or across; cover.
- To overwhelm; to press excessively upon.
- To lie over (someone, especially a child) in order to smother it; to suffocate.
- To put an overlay on.
- Overlaid ornamentation