Blissful Welsh girl supporting Cambs city (7)
I believe the answer is:
elysian
'blissful' is the definition.
(elysian can mean like paradise)
'welsh girl supporting cambs city' is the wordplay.
'welsh girl' becomes 'sian' (common Welsh name).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'cambs city' becomes 'ely' (city in Cambridgeshire).
'sian' after 'ely' is 'ELYSIAN'.
(Other definitions for elysian that I've seen before include "Pertaining to divine fields" , "of the most beautiful fields" , "... Fields, final resting place of the souls of Greek heroes" , "Of abode of the blessed dead in Greek mythology" , "Like paradise" .)