Confidential Catholic girl provided current education (10)
I believe the answer is:
classified
'confidential' is the definition.
(similar in meaning)
'catholic girl provided current education' is the wordplay.
'catholic' becomes 'C' (abbreviation as in RC for Roman Catholic).
'girl' becomes 'lass' (lass can informally mean a girl).
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'current' becomes 'I' (symbol for electric current).
'education' becomes 'ed' (abbreviation - e.g. sex ed).
'c'+'lass'+'if'+'i'+'ed'='CLASSIFIED'
(Other definitions for classified that I've seen before include "Categorised; secret" , "Ordered" , "Arranged in categories" , "to be kept secret" .)