Ground where reptile doesn’t keep quiet (7)
I believe the answer is:
terrain
'ground' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
(Other definitions for terrain that I've seen before include "Landscape" , "Piece of ground" , "Stretch of land of a particular sort" , "Physical feature of a stretch of ground" , "Ground (conditions)" .)