Vagrant carrying one’s information file (7)
I believe the answer is:
dossier
'information file' is the definition.
'dossier' can be an answer for 'file' (both can mean a collection of information). I'm not sure about the 'information' bit.
'vagrant carrying one's' is the wordplay.
'vagrant' becomes 'dosser' (informal term for a vagrant).
'carrying' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'dosser' placed around 'i' is 'DOSSIER'.
Can you help me to learn more?
(Other definitions for dossier that I've seen before include "File of papers (sometimes dodgy)" , "Collection of documents on a topic" , "File of documents" , "brief" , "Papers containing detailed information about a particular person" .)