Scrutiny of old French friend leading state (11)
I believe the answer is:
examination
'scrutiny' is the definition.
('examination' can be a synonym of 'scrutiny')
'old french friend leading state' is the wordplay.
'old' becomes 'ex'.
'french friend' becomes 'ami' (I've seen this before).
'leading' is a charade indicator (letters next to each other).
'state' becomes 'nation' ('nation' can be a synonym of 'state'**).
'ex'+'ami'+'nation'='EXAMINATION'
'of' is the link.
(Other definitions for examination that I've seen before include "School test" , "Formal test" , "Test of proficiency" , "trial" , "Detailed inspection" .)