Crop produced by real cultivation (6)
I believe the answer is:
barley
'crop' is the definition.
(I've seen this before)
'by real cultivation' is the wordplay.
'by real' can be anagrammed to 'BARLEY'.
But, I'm not clear how this is indicated.
'produced' acts as a link.
Can you help me to learn more?
(Other definitions for barley that I've seen before include "Cereal used in beer" , "Grain used in brewing" , "Grain used in making beer" , "Cereal grass" , "Hardy cereal" .)