The most common and most likely answer to this crossword clue is the 10 letter word CONTRACTED
I've seen this crossword clue in The Daily Telegraph
C
O
N
T
R
A
C
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D
Buddy explains!
The straight part
We know that "Given a legal document/shortened" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case given a legal document/shortened = contracted.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 CONTRACTED mean?
CONTRACTED verb- To draw together or nearer; to shorten, narrow, or lessen.
- (grammar) To shorten by omitting a letter or letters or by reducing two or more vowels or syllables to one.
- To enter into a contract with.
- To enter into, with mutual obligations; to make a bargain or covenant for.
- To make an agreement or contract; to covenant; to agree; to bargain.
- To bring on; to incur; to acquire.
- To gain or acquire (an illness).
- To draw together so as to wrinkle; to knit.
- To betroth; to affiance.
- Arranged by contract; established by agreement.
- Made smaller by contraction.
- Incurred; acquired.