Expressed alarm saying this beast could fly (9)
I believe the answer is:
pterosaur
'expressed alarm saying this beast could fly' is the definition.
'pterosaur' can be an answer for 'beast' (pterosaur is a kind of beast). I am not sure about the remainder of the definition.
This is all the clue.
Can you help me to learn more?
(Other definitions for pterosaur that I've seen before include "Old reptile" , "very old flier" , "Extinct flying reptile" , "ancient flyer" , "that once flew" .)