Bad turn as it happens (4)
I believe the answer is:
live
'as it happens' is the definition.
(as in live television)
'bad turn' is the wordplay.
'bad' becomes 'evil' ('evil' is associated in meaning with 'bad').
'turn' says the letters should be written in reverse.
'evil' written backwards gives 'LIVE'.
(Other definitions for live that I've seen before include "Being performed at the time of hearing or viewing" , "Be - unrecorded" , "Of TV programme, seen while taking place" , "Survive" , "Present in person, not recorded" .)