Dish as ordered by boy (5)
I believe the answer is:
Here is my best explanation:
'dish' is the definition.
(salad is a kind of dish)
'as ordered by boy' is the subsidiary indication.
'ordered' indicates anagramming the letters.
'by' is a charade indicator (letters next to each other).
'boy' becomes 'lad' (lad is a kind of boy**).
'as' with letters rearranged gives 'sa'.
(Other definitions for salad that I've seen before include "Vegetable dish", "Cold dish of veg and herbs", "Cold meal", "Raw, green, veg", "- Days (musical)", "Lettuce dish", "healthy food", "Green, potato, Russian or Waldorf?", "Dish of cold vegetables" and "A dish of lettuce and vegetables".)