Mother joining Church of England staff (4)
I believe the answer is:
mace
'staff' is the definition.
(mace is a kind of staff)
'mother joining church of england' is the wordplay.
'mother' becomes 'ma' (ma is a kind of mother).
'joining' is a charade indicator (letters next to each other).
'church of england' becomes 'ce' (abbreviation).
'ma'+'ce'='MACE'
(Other definitions for mace that I've seen before include "put on the rack?" , "Staff - ground nutmeg" , "Came to get nutmeg spice" , "Tear gas - spice" , "Spiked club" .)