Bloodsucker's escape being broadcast (4)
I believe the answer is:
flea
'bloodsucker's' is the definition.
(I've seen this before)
'escape being broadcast' is the wordplay.
'escape' becomes 'flee' (I've seen this before).
'being broadcast' shows a homophone (sound like) (how the word might sound on the radio or TV).
'flee' sounds like 'FLEA'.
(Other definitions for flea that I've seen before include "Circus insect?" , "Small blood-sucking insect" , "high-jumper" , "Blood-sucking parasites" , "Small jumper in small circus" .)