Criticise extremely idiotic hysteria (5)
I believe the answer is:
panic
'hysteria' is the definition.
(hysteria is uncontrollable panic)
'criticise extremely idiotic' is the wordplay.
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'extremely' suggests removing the centre (only the extremes of the word are used).
'idiotic' with its centre taken out is 'ic'.
'pan'+'ic'='PANIC'
(Other definitions for panic that I've seen before include "Contagious fear" , "Have kittens" , "Flap" , "Widespread fear" , "Mad rush (to do something)" .)