Garnish leaf (5)
I believe the answer is:
cress
'garnish leaf' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cress that I've seen before include "bit of salad" , "Food item" , "Cruciferous salad plant" , "Salad vegetable" , "Salad plant paired with mustard" .)