Entertainer that's attractive to a parasite? (4)
I believe the answer is:
host
This clue is a double definition.
'entertainer' is the first definition.
(person hosting or entertaining guests)
'that's attractive to a parasite?' is the second definition.
(a parasite needs a host)
(Other definitions for host that I've seen before include "Party-giver" , "Compre" , "Compere; multitude" , "This man entertains" , "One receiving guests" .)