The environment's getting harder (7)
I believe the answer is:
setting
This clue is a double definition.
'the environment's' is the first definition.
(setting is a kind of environment)
'getting harder' is the second definition.
(Other definitions for setting that I've seen before include "Scene" , "An event's location; hardening" , "Place where an event takes place" , "Surroundings of a place" , "Mount for gem" .)