Swing a scythe (4)
I believe the answer is:
reap
'swing a scythe' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for reap that I've seen before include "Save harvest, glean" , "'As you sow, so shall you . . . .'" , "Glean or cut as harvest" , "Get -- derive" , "Cut and gather (crop)" .)