Fate affected mood (4)
I believe the answer is:
doom
'fate' is the definition.
(I know that doom is a type of fate)
'affected mood' is the wordplay.
'affected' is an anagram indicator.
'mood' is an anagram of 'DOOM'.
(Other definitions for doom that I've seen before include "Catastrophe" , "Fate; ruin" , "Mood of grim fate" , "Fate, destiny" , "Inescapable fate" .)