Ancient vampire bats fly without wings (8)
I believe the answer is:
primeval
'ancient' is the definition.
(I've seen this before)
'vampire bats fly without wings' is the wordplay.
'bats' is an anagram indicator (slang for mad).
'without wings' indicates the central letters (the letters on the edges might be called wings).
The middle letter of 'fly' is 'l'.
'vampire' is an anagram of 'primeva'.
'primeva'+'l'='PRIMEVAL'
(Other definitions for primeval that I've seen before include "From the earliest times" , "Instinctive" , "Ancient" , "Very old" , "having come first in history" .)