Edible plant, a food under review, originally (6)
I believe the answer is:
radish
'edible plant' is the definition.
'radish' can be an answer for 'plant' (radish plant is a kind of plant). I'm not certain of the 'edible' bit.
'a food under review originally' is the wordplay.
'food' becomes 'dish' (dish is a kind of food).
'under' says to put letters next to each other (in a down clue, some letters go below others).
'originally' suggests taking the first letters.
The first letter of 'review' is 'r'.
'a'+'dish'='adish'
'adish' after 'r' is 'RADISH'.
Can you help me to learn more?
(Other definitions for radish that I've seen before include "Root eaten raw in salads" , "Pungent fleshy edible root eaten in salads" , "Pungent, red salad vegetable" , "Hottish salad plant" , "Bit of salad" .)