Completely happy and contented (8)
I believe the answer is:
blissful
'completely happy and contented' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for blissful that I've seen before include "Ecstatic, rapturously happy" , "Delighted" , "Joyous, rapt" , "Completely happy and contented" , "Happy, often delusively" .)