Cathedral housing this writer's books in particular (9)
I believe the answer is:
eminently
'in particular' is the definition.
(eminently can mean particularly or greatly)
'cathedral housing this writer's books' is the wordplay.
'cathedral' becomes 'ely' (cathedral city in Cambridgeshire).
'housing' is an insertion indicator.
'this writer's' becomes 'mine' (belonging to the crossword setter).
'books' becomes 'NT' (abbreviation for New Testament).
'mine'+'nt'='minent'
'ely' enclosing 'minent' is 'EMINENTLY'.
(Other definitions for eminently that I've seen before include "to a notable extent" , "well" , "In an outstanding manner" .)