Greek-salad ingredient (5)
I believe the answer is:
olive
'greek-salad ingredient' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for olive that I've seen before include "Evergreen Mediterranean tree" , "Oily stone fruit" , "Mediterranean tree-fruit, nice in cocktail" , "Fruit; Popeye's girlfriend" , "Yellowy-green colour and fruit" .)