A new church ceremony installs Oxford’s first hermit (9)
I believe the answer is:
anchorite
'hermit' is the definition.
(I know that hermit can be written as anchorite)
'a new church ceremony installs oxford's first' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'church' becomes 'ch' (common abbreviation).
'ceremony' becomes 'rite' (rite is a kind of ceremony).
'installs' indicates putting letters inside.
'oxford's first' becomes 'o' (1st letter of 'oxford').
'ch'+'rite'='chrite'
'chrite' placed around 'o' is 'chorite'.
'a'+'n'+'chorite'='ANCHORITE'
(Other definitions for anchorite that I've seen before include "A solitary person" , "Religious recluse (hist.)" , "Hermit or religious recluse" , "Loner" , "Holy recluse" .)