Splendid for Greta, possibly (5)
I believe the answer is:
great
'splendid' is the definition.
(I've seen this in another clue)
'greta possibly' is the wordplay.
'possibly' indicates an anagram.
'greta' anagrammed gives 'GREAT'.
'for' is the 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" .)