Glum, the (eventual) result of not spitting feathers? (4,2,3,5)
I believe the answer is:
down in the dumps
'glum the eventual result' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'not spitting feathers?' is the wordplay.
I cannot really understand how this works, but
'not' could be 'nt' (synonyms) and 'nt' is found in the answer.
'feathers?' could be 'down' (down can mean bird feathers) and 'down' is found in the answer.
This explanation may well be incorrect...
'of' acts as a link.
(Other definitions for down in the dumps that I've seen before include "Scavengers may be" , "Blue" , "feathers among the rubbish?" , "depressed" .)