Splendid for Greta, possibly (5)
I believe the answer is:
great
'splendid' is the definition.
(thesaurus)
'greta possibly' is the wordplay.
'possibly' indicates an anagram.
'greta' with letters rearranged gives 'GREAT'.
'for' acts as a link.
(Other definitions for great that I've seen before include "Mum's dad's mum, for example" , "1963 Buckinghamshire mail van raid" , "'Goodness gracious -- -- -- --' (pop song)" , "Big, large" , "Waterbird" .)