Church cellist has CIA case reviewed (14)
I believe the answer is:
ecclesiastical
'church' is the definition.
(relating to the church)
'cellist has cia case reviewed' is the wordplay.
'has' is a charade indicator (letters next to each other).
'reviewed' is an anagram indicator (letters reviewed or revised).
'cia'+'case'='ciacase'
'cellist' after 'ciacase' is 'ciacasecellist'.
'ciacasecellist' is an anagram of 'ECCLESIASTICAL'.
(Other definitions for ecclesiastical that I've seen before include "Of the church or clergy" , "Clergy's" , "Relating to the Christian church" , "Belonging to the church" .)