The most common and most likely answer to this crossword clue is the 9 letter word ETYMOLOGY
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More clues leading to the result ETYMOLOGY
Buddy explains!

The straight part
We know that "Original root" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case original root = etymology.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 ETYMOLOGY mean?
ETYMOLOGY noun- The study of the historical development of languages, particularly as manifested in individual words.
- The origin and historical development of a word; the derivation.
- An account of the origin and historical development of a word as presented in a dictionary or the like.