Formerly part of coronation ceremony (4)
I believe the answer is:
once
'formerly' is the definition.
('once' can be a synonym of 'formerly')
'part of coronation ceremony' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'ONCE' is hidden in the letters of 'coronation ceremony'.
(Other definitions for once that I've seen before include "Previously" , "In times past" , "yesterday" , "In days past" , "At some former time" .)