This year rioting shows wild emotionalism (8)
I believe the answer is:
hysteria
'wild emotionalism' is the definition.
(I've seen this before)
'this year rioting' is the wordplay.
'rioting' indicates an anagram.
'this'+'year'='thisyear'
'thisyear' is an anagram of 'HYSTERIA'.
'shows' acts as a link.
(Other definitions for hysteria that I've seen before include "Uncontrollable emotion -- this year (anag)" , "highly emotional state" , "Extreme emotional state of instability" , "Is hearty about losing the plot" , "Wild emotionalism" .)