Bloodsucking vampire occasionally travelling from the east is heartless (9)
I believe the answer is:
parasitic
'bloodsucking' is the definition.
('parasitic' can be a synonym of 'bloodsucking')
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for parasitic that I've seen before include "Sponging" , "Such threats" , "like a leech" , "to be paid for by someone else" , "Living on another like flea" .)