Show Eve’s first-born rising as one possessed by the devil (8)
I believe the answer is:
demoniac
'the devil' is the definition.
(demoniac is a kind of devil)
'show eve's first-born rising' is the wordplay.
'show' becomes 'demo' (I've seen this before).
'eve's first-born' becomes 'cain' (I am not sure about this - if you are sure you should believe this answer much more).
'rising' says the letters should be written in reverse (going up in a down clue).
'cain' in reverse letter order is 'niac'.
'demo'+'niac'='DEMONIAC'
'as one possessed by' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for demoniac that I've seen before include "Diabolical" , "Person possessed by an evil spirit" , "Comedian of frenzied sort" , "man possessed" , "Comedian of devilish sort 98)" .)