The most common and most likely answer to this crossword clue is the 12 letter word BLUE-BLOODED
B
L
U
E
-
B
L
O
O
D
E
D
More clues leading to the result BLUE-BLOODED
Buddy explains!
The straight part
We know that "Born high" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case born high = blue-blooded.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.