Very eccentric vampires? (4)
I believe the answer is:
bats
I believe this is a double definition.
'very eccentric' is the first definition.
(I've seen this before)
'vampires?' is the second definition.
(I've seen this in another clue)
(Other definitions for bats that I've seen before include "Mad; mammals" , "bananas" , "Lunatic" , "Those striking" , "Mad - nocturnal creatures" .)