A club to set up church teaching? Proper shambles (8)
I believe the answer is:
abattoir
'proper shambles' is the definition.
(shambles could historically mean a slaughterhouse)
'a club to set up church teaching?' is the wordplay.
'club' becomes 'bat' (as in sporting equipment).
'set up' says the letters should be written backwards (in a down clue, letters go up).
'church teaching?' becomes 'RI' (Religious Instruction).
'ri' written backwards gives 'ir'.
'a'+'bat'+'to'+'ir'='ABATTOIR'
(Other definitions for abattoir that I've seen before include "A slaughter house for cattle" , "Animal slaughter-house" , "it makes a killing" , "Building for butchering animals" , "stunning location" .)