Broadcast overlooked film (4)
I believe the answer is:
mist
'film' is the definition.
(to film over is to mist or fog over)
'broadcast overlooked' is the wordplay.
'broadcast' indicates a 'sounds like' (homophone) clue (how the word might sound on the radio or TV).
'overlooked' becomes 'missed' ('miss' can be a synonym of 'overlook').
'missed' sounds like 'MIST'.
(Other definitions for mist that I've seen before include "Haze" , "Fine spray" , "Fret" , "Watery film" , "Slight fog" .)