Salad ingredient artist portrayed by plate (6)
I believe the answer is:
radish
'salad ingredient' is the definition.
(I've seen this before)
'artist portrayed by plate' is the wordplay.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'portrayed by' says to put letters next to each other.
'plate' becomes 'dish' (I've seen this before).
'ra'+'dish'='RADISH'
(Other definitions for radish that I've seen before include "Small red salad vegetable" , "Edible small root" , "Sir had this vegetable" , "Plant with crisp root eaten raw" , "Hard vegetable" .)