Hate rodents eating nearly everything (6)
I believe the answer is:
malice
'hate' is the definition.
(malice is a kind of hate)
'rodents eating nearly everything' is the wordplay.
'rodents' becomes 'mice' (mouse is a kind of rodent).
'eating' is an insertion indicator.
'nearly' means to remove the last letter.
'everything' becomes 'all' (I've seen this before).
'all' with its last letter removed is 'al'.
'mice' placed around 'al' is 'MALICE'.
(Other definitions for malice that I've seen before include "Spite, venom" , "Hate" , "Spiteful, animosity, sometimes a forethought" , "Spite and rancour" , "Bitterness" .)