Plant from unusual calm site (8)
I believe the answer is:
clematis
'plant' is the definition.
(type of plant)
'unusual calm site' is the wordplay.
'unusual' indicates an anagram.
'calm'+'site'='calmsite'
'calmsite' is an anagram of 'CLEMATIS'.
'from' is the link.
(Other definitions for clematis that I've seen before include "Where man meets machine" , "it may cover walls" , "traveller's joy" , "Popular climbing plant" , "bloomer" .)