Hostile feeling (6)
I believe the answer is:
animus
'hostile feeling' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for animus that I've seen before include "Hostility shown in speech or action" , "Hostility, bad feeling toward" , "Motivating spirit" , "Deep-seated hostility or vital force" , "Malicious ill-will" .)