Bat in centre of Oval, Dickie Bird once blowing his top (7)
I believe the answer is:
vampire
'bat' is the definition.
(vampire bat is a type of bat)
'centre of oval dickie bird once blowing his top' is the wordplay.
'centre of' indicates the central letters.
'dickie bird once' becomes 'umpire' (Dickie Bird was a cricket umpire).
'blowing his top' means to remove the first letter.
The middle of 'oval' is 'va'.
'umpire' with its first letter taken away is 'mpire'.
'va'+'mpire'='VAMPIRE'
'in' is the link.
(Other definitions for vampire that I've seen before include "Legendary dead body that sucks blood" , "eg Dracula" , "Transylvanian bloodsucker" , "Dracula is one" , "A blood-sucker like Dracula" .)