Picaroon is entertained by Tramp in some papers (7)
I believe the answer is:
dossier
'some papers' is the definition.
(I've seen this before)
'picaroon is entertained by tramp' is the wordplay.
'picaroon' becomes 'I' (where the crossword setter is 'Picaroon').
'is entertained by' is an insertion indicator (entertain can mean to host or welcome in).
'tramp' becomes 'dosser' (dosser is a kind of tramp).
'i' placed into 'dosser' is 'DOSSIER'.
'in' acts as a link.
(Other definitions for dossier that I've seen before include "File of papers (sometimes dodgy)" , "Record" , "Report" , "brief" , "Collection of documents on a topic" .)