Rough sleeper should keep one written account (7)
I believe the answer is:
dossier
'written account' is the definition.
(dossier is a kind of written account)
'rough sleeper should keep one' is the wordplay.
'rough sleeper' becomes 'dosser' (I've seen this before).
'should keep' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'dosser' placed around 'i' is 'DOSSIER'.
(Other definitions for dossier that I've seen before include "Collection of documents on a subject" , "Report" , "File of papers (sometimes dodgy)" , "Set of papers" , "Papers containing detailed information about a particular person" .)