Extinct reptile (8)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
dinosaur
'extinct reptile' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for dinosaur that I've seen before include "old-fashioned sort" , "Out of date person or thing" , "is well out of date" , "Creature no longer" , "Beast long gone" .)