Being dejected, give discontented girl ultimatum (4)
I believe the answer is:
glum
'being dejected' is the definition.
('glum' can be similar in meaning to 'dejected')
'give discontented girl ultimatum' is the wordplay.
'give' is a charade indicator (letters next to each other).
'discontented' says to hollow out the word (remove centre letters) (the word's contents are removed).
'ultimatum' becomes 'um' (I can't explain this - if you can you should believe this answer much more).
'girl' with its centre removed is 'gl'.
'gl' put next to 'um' is 'GLUM'.
Can you help me to learn more?
(Other definitions for glum that I've seen before include "Blue" , "Doleful" , "Sad, down-in-th-mouth" , "Down at the mouth, gloomy" , "Unhappy" .)