Scheme has the edge (3)
I believe the answer is:
hem
'the edge' is the definition.
(I've seen this in another clue)
'scheme has' is the wordplay.
'has' indicates a hidden word.
'HEM' is hidden in the letters of 'scheme'.
(Other definitions for hem that I've seen before include "try to attract attention" , "Finished edge of a piece of cloth" , "Border; fringe" , "Part of skirt" , "Sewn edge to fabric" .)