Documents contents of grey trousers (7)
I believe the answer is:
records
'documents' is the definition.
(record is a kind of document)
'contents of grey trousers' is the wordplay.
'contents of' says to take the centre (the letters on the inside of the word).
'trousers' becomes 'cords' (cords is a kind of trousers).
The centre of 'grey' is 're'.
're'+'cords'='RECORDS'
(Other definitions for records that I've seen before include "LPs, e.g." , "Makes written note" , "Annotations of events" , "The best (or worst) performances ever" , "Files" .)