Green vines winding round the tops of oaks, unusually (7)
I believe the answer is:
envious
'green' is the definition.
(thesaurus)
'vines winding round the tops of oaks unusually' is the wordplay.
'winding' is an anagram indicator.
'round' means one lot of letters goes inside another.
'the tops of' indicates taking the first letters.
The first letters of 'oaks unusually' is 'ou'.
'vines' is an anagram of 'envis'.
'envis' placed around 'ou' is 'ENVIOUS'.
(Other definitions for envious that I've seen before include "Full of jealousy" , "Feeling jealousy" , "Green, in emotion" , "Begrudging another's fortune" , "resentful" .)