Satan in angry mood about Christ ultimately (7)
I believe the answer is:
tempter
'satan' is the definition.
(I know that satan can be written as Tempter)
'mood about christ ultimately' is the wordplay.
'mood' becomes 'temper' (temper is one's mood or state of mind).
'about' is an insertion indicator.
'ultimately' says to take the final letters.
The last letter of 'christ' is 't'.
'temper' going around 't' is 'TEMPTER'.
'in angry' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for tempter that I've seen before include "One who entices to do wrong" , "The Devil?" , "Siren" , "Satan" , "seducer" .)