Bearing stand for broadcast (4)
I believe the answer is:
mien
'bearing' is the definition.
(I know that bearing can be written as mien)
'stand for broadcast' is the wordplay.
'stand for' becomes 'mean' (synonyms).
'broadcast' indicates a 'sounds like' (homophone) clue (how the word might sound on the radio or TV).
'mean' sounds like 'MIEN'.
(Other definitions for mien that I've seen before include "A face - maybe mine" , "Appearance is strangely mine" , "aspect" , "The carriage" , "attitude" .)