Female uncertain about God? That is symptomatic (10)
I believe the answer is:
diagnostic
'is symptomatic' is the definition.
(synonyms)
'female uncertain about god?' is the wordplay.
'female' becomes 'di' (short for Diana).
'uncertain about god?' becomes 'agnostic' (I can't explain this - if you can you should give a lot more credence to this answer).
'di'+'agnostic'='DIAGNOSTIC'
'that' is the link.
Can you help me to learn more?
(Other definitions for diagnostic that I've seen before include "Distinctive symptom or characteristic (of a disease)" , "Analytical" , "Indicating the nature of an illness" , "Computer program" .)