Green pasta sauce (5)
I believe the answer is:
pesto
'green pasta sauce' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pesto that I've seen before include "Ligurian food" , "Basic sauce" , "Pasta sauce mainly of basil and cheese" , "sauce involving Basil" , "Saucy work" .)