Outside this place a theologian held fast (7)
I believe the answer is:
adhered
'held fast' is the definition.
('adhere' can be a synonym of 'hold fast')
'outside this place a theologian' is the wordplay.
'outside' is an insertion indicator.
'this place' becomes 'here' (I've seen this in other clues**).
'theologian' becomes 'dd' (Doctor of Divinity degree).
'a'+'dd'='add'
'here' placed into 'add' is 'ADHERED'.
(Other definitions for adhered that I've seen before include "Stuck; glued" , "Stuck (to something)" , "Stuck to, remained loyal" , "Showed sticking power" , "Stuck - redhead (anag)" .)