Biographical sketch is for dossier (7)
I believe the answer is:
profile
'biographical sketch' is the definition.
(thesaurus)
'for dossier' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'dossier' becomes 'file' (a dossier is a file or set of information).
'pro'+'file'='PROFILE'
'is' is the link.
(Other definitions for profile that I've seen before include "Sideways view" , "Sideways outline" , "View from one side" , "image" , "Short biographical sketch" .)