Plant in orderly system (6)
I believe the answer is:
cosmos
I believe this is a double definition.
'plant' is the first definition.
'orderly system' is the second definition.
'in' is the link.
(Other definitions for cosmos that I've seen before include "The universe, whole of creation" , "Universe as an ordered system" , "Universe as an ordered whole" , "The universe - a daisy" , "Everything that exists" .)