Cropper.
He came a cropper. He fell head over heels. To get a cropper. To get a bad fall. “Neck and crop” means altogether, and to “come a cropper” is to come to the ground neck and crop.
· 
· 
Entry taken from Dictionary of Phrase and Fable, edited by the Rev. E. Cobham Brewer, LL.D. and revised in 1895.