Feel animosity to writer over trial (6)
I believe the answer is:
detest
'feel animosity to' is the definition.
I can't judge whether this defines the answer.
'writer over trial' is the wordplay.
'writer' becomes 'ed' (I've seen this in other clues**).
'over' is a reversal indicator.
'trial' becomes 'test' ('test' can be a synonym of 'trial').
'ed' backwards is 'de'.
'de'+'test'='DETEST'
(Other definitions for detest that I've seen before include "Dislike intensely, loathe" , "Dislike intensely, think badly of" , "Loathe, hate intensely" , "Having a loathing" , "Deplore" .)