The most common and most likely answer to this crossword clue is the 9 letter word TELLURIAN
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More clues leading to the result TELLURIAN
Buddy explains!
The straight part
We know that "Earthling" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case earthling = tellurian.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 TELLURIAN mean?
TELLURIAN noun- An inhabitant of the Earth.
- Of or relating to the earth; (specifically) inhabiting planet Earth as opposed to other planets.
- Of a mineral: containing tellurium.
- An instrument used to show how the rotation of the Earth on its axis and its orbit around the Sun cause day and night and the seasons.