See majestic old crown saint's wearing (10)
I believe the answer is:
episcopate
'see' is the definition.
(I've seen this before)
'majestic old crown saint's wearing' is the wordplay.
'majestic' becomes 'epic' (both can mean grand).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'crown' becomes 'pate' (both can mean a person's head).
'saint' becomes 's'.
'wearing' indicates putting letters inside.
'epic'+'o'+'pate'='epicopate'
'epicopate' going around 's' is 'EPISCOPATE'.
(Other definitions for episcopate that I've seen before include "Bishopric" , "clergyman's office" , "bishop's office" , "See" .)