Greens in one block reflected on black material (8)
I believe the answer is:
kohlrabi
'greens' is the definition.
The definition and answer can be both things that one consumes for nourishment as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'one block reflected on black material' is the wordplay.
'one' becomes 'i' (Roman numeral).
'block' becomes 'bar' (block can mean to ban or bar).
'reflected' shows that the letters should be reversed in order.
'on' means one lot of letters go next to another.
'black material' becomes 'kohl' (I can't explain this - if you can you should give a lot more credence to this answer).
'i'+'bar'='ibar'
'ibar' backwards is 'rabi'.
'rabi' put after 'kohl' is 'KOHLRABI'.
'in' is the link.
Can you help me to learn more?
(Other definitions for kohlrabi that I've seen before include "vegetable" , "leaves to be consumed" , "Variety of cabbage like a turnip" .)