Bliss in happy house westbound river devours (8)
I believe the answer is:
'bliss' is the definition.
(I've seen this in another clue)
'happy house westbound river devours' is the wordplay.
I cannot quite understand how this works, but
'happy' could be 'up' (I've seen this in other clues) and 'up' is found within the answer.
'house' could be 'ho' (abbreviation for house) and 'ho' is present in the answer.
'river' could be 'ria' and 'ria' is found in the answer.
A single letter 'e' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for euphoria that I've seen before include "Intense happiness and elation", "transport", "Intense happy feeling", "Intense feeling of happiness", "A feeling of wild happiness and well-being".)