The most common and most likely answer to this crossword clue is the 7 letter word *TERRA*
I've seen this crossword clue in The Guardian
*
T
E
R
R
A
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Buddy explains!

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 *TERRA* mean?
*TERRA* noun- (astrogeology) A rough upland or mountainous region of the Moon with a relatively high albedo.