Northern idiot entertaining rogue in set showing spite (9)
I believe the answer is:
nastiness
'spite' is the definition.
('nastiness' can be a synonym of 'spite')
'northern idiot entertaining rogue in set' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'idiot' becomes 'ass' (I've seen this before**).
'entertaining' indicates putting letters inside.
'rogue' indicates an anagram.
'in'+'set'='inset'
'inset' anagrammed gives 'tines'.
'ass' going around 'tines' is 'astiness'.
'n'+'astiness'='NASTINESS'
'showing' acts as a link.
(Other definitions for nastiness that I've seen before include "Malevolence" , "Pollution" , "ill humour" , "Repugnant behaviour" , "repugnance" .)