Arrive with a harvester — and have a terrible fall! (4,1,7)
I believe the answer is:
come a cropper
'have a terrible fall' is the definition.
'arrive with a harvester' is the wordplay.
'arrive' becomes 'come' (coming is a kind of arriving).
'with' says to put letters next to each other.
'harvester' becomes 'cropper'.
'come'+'a'+'cropper'='COME A CROPPER'
'and' acts as a link.
(Other definitions for come a cropper that I've seen before include "Suffer a defeat" , "Fail spectacularly" , "Fail badly" , "Fall heavily and unexpectedly" .)