Shock hospital broadcast (4)
I believe the answer is:
hair
'shock' is the definition.
(I've seen this before)
'hospital broadcast' is the wordplay.
'hospital' becomes 'h'.
'broadcast' becomes 'air' ('air' can be a synonym of 'broadcast').
'h'+'air'='HAIR'
(Other definitions for hair that I've seen before include "Growth from skin" , "It grows from a follicle" , "Hirsute hippy musical with song 'aquarius'" , "Fur - mop" , "Bristle" .)