The most common and most likely answer to this crossword clue is the 5 plus 4 letter word TITLE DEED
I've seen this crossword clue in Financial Times
T
I
T
L
E
D
E
E
D
More clues leading to the result TITLE DEED
- Proof of ownership? Doctor deleted it
- Legal document fool took across river
- Appropriate document to be landed with?
- Expression of ownership, like a lord claiming river
- Championship achievement leads to transfer
- It will prove ownership of river in named setting
- This document supports your claim for publication of French edition
- It’s proved right – They Do It With Mirrors? …
- … deleted by mistake after note; here’s another document
- Called before finishing journalist’s legal document
Buddy explains!
The straight part
We know that "This document supports your claim" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this document supports your claim = title deed.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.