Live with a marvellous, sin-free divine? (8)
I believe the answer is:
beatific
'divine?' is the definition.
(thesaurus)
'live with a marvellous sin-free' is the wordplay.
I cannot really see how this works, but
'live' could be 'be' (synonyms) and 'be' is present in the answer.
'a' is within the answer.
This explanation may well be incorrect...
(Other definitions for beatific that I've seen before include "Feeling or expressing blissful happiness" , "Angelic, saintly" , "supremely happy" , "Joyful" , "Saintly, blessed" .)