Old lady joining church club (4)
I believe the answer is:
mace
'club' is the definition.
(thesaurus)
'old lady joining church' is the wordplay.
'old lady' becomes 'ma'.
'joining' is a charade indicator (letters next to each other).
'church' becomes 'ce' (abbreviation for Church of England**).
'ma'+'ce'='MACE'
(Other definitions for mace that I've seen before include "Spice; ceremonial baton" , "Tear gas - spice" , "Came to get nutmeg spice" , "put on the rack?" , "Staff of office and a spice" .)