Number rejected by Anglicans in the past (4)
I believe the answer is:
once
'in the past' is the definition.
(I've seen this before)
'number rejected by anglicans' is the wordplay.
'number' becomes 'no' (abbreviation for 'number'**).
'rejected' says the letters should be written in reverse.
'by' is a charade indicator (letters next to each other).
'anglicans' becomes 'ce' (Church of England).
'no' in reverse letter order is 'on'.
'on'+'ce'='ONCE'
(Other definitions for once that I've seen before include "A single time" , "... upon a time for the storyteller" , "Cone (anag.)" , "in days of yore?" , "In days past" .)