Misses careless broadcast (5)
I believe the answer is:
lacks
'misses' is the definition.
(lacking is a kind of missing)
'careless broadcast' is the wordplay.
'careless' becomes 'lax' ('lax' can be a synonym of 'careless').
'broadcast' indicates a 'sounds like' (homophone) clue (how the word might sound on the radio or TV).
'lax' is a homophone of 'LACKS'.
(Other definitions for lacks that I've seen before include "Is without, wants" , "Needs" , "Doesn't have" , "Has a want" , "Wants, is deficient in" .)