Green Day finding fame (9)
I believe the answer is:
limelight
'fame' is the definition.
(I've seen this in another clue)
'green day' is the wordplay.
'green' becomes 'lime' (lime is a shade of green).
'day' becomes 'light' (I've seen this in other clues).
'lime'+'light'='LIMELIGHT'
'finding' acts as a link.
(Other definitions for limelight that I've seen before include "Focus of attention" , "centre of public attention" , "Celebrity" , "(In the) public eye" , "Chaplin 1952 film" .)