This year is affected by emotional instability (8)
I believe the answer is:
hysteria
'emotional instability' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'this year is affected' is the wordplay.
'is affected' indicates anagramming the letters.
'this'+'year'='thisyear'
'thisyear' with letters rearranged gives 'HYSTERIA'.
'by' is the link.
Can you help me to learn more?
(Other definitions for hysteria that I've seen before include "neurotic disorder" , "Delirium - nervous disorder" , "Wild excitement" , "Emotional and uncontrollable outburst" , "Emotional frenzy" .)