Hysterical (8)
I believe the answer is:
neurotic
'hysterical' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for neurotic that I've seen before include "Over-anxious" , "Subject to excessive anxiety and behaviour" , "Emotionally disturbed" , "obsessive character" , "I counter in being subject to abnormal anxieties" .)