Always envious, for constantly popular person (9)
I believe the answer is:
evergreen
'constantly popular person' is the definition.
'always envious' is the wordplay.
'always' becomes 'ever' ('ever' can be a synonym of 'always').
'envious' becomes 'green'.
'ever'+'green'='EVERGREEN'
'for' is the link.
(Other definitions for evergreen that I've seen before include "Holly's one" , "Like Laurel" , "Ageless" , "Standard - type of shrub" , "Plant with leaves all year round" .)