Possible Clues:

• Mortarboard addition
• That hangs down, but not so much of it at the other way
• Part of maize plant rejected for fear that it contains arsenic
• Corn tuft
• This will hang down, but not so much at the back (6)
• Graduation-cap ornament
• Corn feature
• Hanging down, but not so much up at it
• It's on the fringe
• Hanger-on perhaps volunteers less, in retrospect