Not aware a French ruler now is entering (9)
I believe the answer is:
unknowing
'not aware' is the definition.
(I've seen this before)
'a french ruler now is entering' is the wordplay.
'a french' becomes 'un' ('a' in French).
'ruler' becomes 'king' (king is a kind of ruler).
'is entering' indicates putting letters inside.
'king' enclosing 'now' is 'knowing'.
'un'+'knowing'='UNKNOWING'
(Other definitions for unknowing that I've seen before include "Not aware" , "Ignorance" , "Lacking awareness" , "Ignorant" .)