Importance of report (7)
I believe the answer is:
account
I believe this clue is a double definition.
'importance' is the first definition.
(thesaurus)
'report' is the second definition.
('account' can be a synonym of 'report')
'of' is the link.
(Other definitions for account that I've seen before include "News report" , "Bank record" , "Reckoning; narrative" , "Report of an event" , "books" .)