Terribly evil, as it happens (4)
I believe the answer is:
live
'as it happens' is the definition.
(as in live broadcasting)
'terribly evil' is the wordplay.
'terribly' indicates anagramming the letters.
'evil' is an anagram of 'LIVE'.
(Other definitions for live that I've seen before include "Eg, from Kingston" , "Heard or seen as the event takes place and not from a recording" , "Carrying current - not pre-recorded" , "Possibly shocking" , "experience" .)