Top cover from hospital broadcast on web (7)
I believe the answer is:
hairnet
'top cover' is the definition.
'hospital broadcast on web' is the wordplay.
'hospital' becomes 'h'.
'broadcast' becomes 'air' ('air' can be a synonym of 'broadcast').
'on' means one lot of letters go next to another.
'web' becomes 'net' ('net' can be a synonym of 'web').
'h'+'air'+'net'='HAIRNET'
'from' is the link.
(Other definitions for hairnet that I've seen before include "Headgear" , "This protects beehive, for instance" , "Lock-keeper" , "The rain (anag) - used after shampooing?" , "It protects locks" .)