Blessed female, see, is very determined (6)
I believe the answer is:
steely
'very determined' is the definition.
(with steely determination)
'blessed female see' is the wordplay.
'blessed female' becomes 'ste' (short for sainte, French feminine form of saint).
'see' becomes 'Ely' (see is a place with a cathedral - e.g. Ely).
'ste'+'ely'='STEELY'
'is' acts as a link.
(Other definitions for steely that I've seen before include "Obdurate" , "Ruthless" , "firm" , "Gimlet-eyed" , "As hard, or grey, as metal" .)