Yet I’m upset about new animosity (6)
I believe the answer is:
enmity
'animosity' is the definition.
(I've seen this in another clue)
'yet i'm upset about new' is the wordplay.
'upset' is an anagram indicator.
'about' indicates putting letters inside.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'yet'+'im'='yetim'
'yetim' anagrammed gives 'emity'.
'emity' going around 'n' is 'ENMITY'.
(Other definitions for enmity that I've seen before include "Deep-seated antagonism" , "Antagonism, ill-will" , "State of deep-seated ill-will" , "Personal hostility" , "Hate; aversion" .)