Hate being unreasonably tested (6)
I believe the answer is:
detest
'hate' is the definition.
(to detest is to hate or loathe)
'unreasonably tested' is the wordplay.
'unreasonably' indicates anagramming the letters.
'tested' is an anagram of 'DETEST'.
'being' is the link.
(Other definitions for detest that I've seen before include "Dislike thoroughly" , "Having a loathing" , "can't stand" , "Not like" , "Abominate" .)