Crossword Genius

Ground where reptile doesn’t keep quiet (7)

Ross

I believe the answer is:

'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)".)

I've seen this clue in The Times.