Position adopted by sacristan ceremoniously (6)
I believe the answer is:
stance
'position' is the definition.
(stance is a kind of position)
'adopted by sacristan ceremoniously' is the wordplay.
'adopted by' says the answer is hidden in the clue.
'STANCE' can be found hidden inside 'sacristan ceremoniously'.
(Other definitions for stance that I've seen before include "Position or attitude taken" , "Standpoint" , "driver preparing to strike" , "Deportment" , "a driver may take on course" .)