Damn peculiar mood (4)
I believe the answer is:
doom
'damn' is the definition.
(to doom someone is to damn or curse them)
'peculiar mood' is the wordplay.
'peculiar' is an anagram indicator (a peculiar or strange ordering of the letters).
'mood' with letters rearranged gives 'DOOM'.
(Other definitions for doom that I've seen before include "Mood of condemnation" , "Curse" , "Bad destiny" , "__ and gloom" , "In the end" .)