Short legal document (5)
I believe the answer is:
brief
This clue is a double definition.
'short' is the first definition.
(similar in meaning)
'legal document' is the second definition.
(I know that brief is a type of legal document)
(Other definitions for brief that I've seen before include "Remit" , "Using few words" , "Document stating the facts of a legal case" , "Case given to a barrister" , "description of Macbeth's candle" .)