Plant from calm site, possibly (8)
I believe the answer is:
clematis
'plant' is the definition.
(type of plant)
'calm site possibly' is the wordplay.
'possibly' indicates anagramming the letters.
'calm'+'site'='calmsite'
'calmsite' with letters rearranged gives 'CLEMATIS'.
'from' is the link.
(Other definitions for clematis that I've seen before include "Old man's beard" , "it may cover walls" , "Climates (anag)" , "flower" , "Climbing plant with colourful flowers" .)