Idle person pinching one’s file (7)
I believe the answer is:
dossier
'file' is the definition.
(both can mean a collection of information)
'idle person pinching one's' is the wordplay.
'idle person' becomes 'dosser' (a dosser is a lazy person).
'pinching' is an insertion indicator (taking inside).
'one' becomes 'i' (Roman numeral).
'dosser' going around 'i' is 'DOSSIER'.
(Other definitions for dossier that I've seen before include "Collection of documents on a subject" , "Papers containing detailed information about a particular person" , "Report" , "Record" , "File of papers (sometimes dodgy)" .)