Nurse, that woman one's seen in church (7)
I believe the answer is:
cherish
'nurse' is the definition.
(I've seen this before)
'woman one's seen in church' is the wordplay.
'woman' becomes 'her' (**).
'one's' becomes 'is' (roman numeral).
'seen in' indicates putting letters inside.
'church' becomes 'ch' (common abbreviation).
'her'+'is'='heris'
'heris' inserted within 'ch' is 'CHERISH'.
'that' acts as a link.
(Other definitions for cherish that I've seen before include "Nurture (a hope)" , "Nurse" , "Hold dear, treasure" , "Protect and treat with affection" , "Protect and care for lovingly" .)