In club a Transylvanian? A vampire? (3)
I believe the answer is:
bat
'a vampire?' is the definition.
(I've seen this in another clue)
'in club a transylvanian?' is the wordplay.
'in' says the answer is hidden in the clue.
'BAT' can be found hidden inside 'club a transylvanian'.
(Other definitions for bat that I've seen before include "Pipistrelle" , "Nocturnal flier" , "Night-flyer" , "Nocturnal mouselike mammal" , "Night flier" .)