The most common and most likely answer to this crossword clue is the 10 letter word FORMALISED
I've seen this crossword clue in The Sunday Telegraph
F
O
R
M
A
L
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S
E
D
Buddy explains!

The straight part
We know that "Given legal status" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case given legal status = formalised.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 FORMALISED mean?
FORMALISED verb- To give something a definite form; to shape.
- To give something a formal or official standing.
- To act with formality.