Terribly evil, as it happens (4)
I believe the answer is:
live
'as it happens' is the definition.
(as in live television)
'terribly evil' is the wordplay.
'terribly' indicates anagramming the letters.
'evil' anagrammed gives '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" .)