Community of organisms and their environment (9)
I believe the answer is:
ecosystem
'community of organisms and their environment' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ecosystem that I've seen before include "integrated community" , "The interaction of a group of organisms with their physical environment" , "Biological community with its environment" , "Community of organisms and their environment" , "orderly collection of organisms" .)