Express disapproval over posh archbishop (4)
I believe the answer is:
tutu
'archbishop' is the definition.
(I've seen this before)
'express disapproval over posh' is the wordplay.
'express disapproval over' becomes 'tut' (I've seen this in other clues).
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'tut'+'u'='TUTU'
(Other definitions for tutu that I've seen before include "Ballet dancer's short skirt" , "North African nation" , "8 [BALLET] term" , "In which dancer may appear" , "Giselle's skirt" .)