Region in Durham is simply wrong (5)
I believe the answer is:
amiss
'wrong' is the definition.
(I know that wrong can be written as amiss)
'region in durham is simply' is the wordplay.
'region in' indicates a hidden word.
'AMISS' is hidden in the letters of 'durham is simply'.
(Other definitions for amiss that I've seen before include "Unsuitable" , "Fallacious" , "Mistaken" , "error" , "Revealing fault" .)