High honour in coming in to reduce hate (9)
I believe the answer is:
abominate
'hate' is the definition.
(abominating is a kind of hating)
'high honour in coming in to reduce' is the wordplay.
'high honour' becomes 'om' (Order of Merit).
'coming in to' indicates putting letters inside.
'reduce' becomes 'abate' (I've seen this before).
'om'+'in'='omin'
'omin' going within 'abate' is 'ABOMINATE'.
(Other definitions for abominate that I've seen before include "Condemn" , "Be revolted by" , "Loathe, find hateful" , "Amoeba nit - easy to loathe" , "Loathe, detest" .)