Topple (5)
'topple' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for upend that I've seen before include "Tip on side" , "Set upside down" , "Stand erect" , "Turn top to bottom" , "Set (something) vertical" .)
'topple' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for overbalance that I've seen before include ""take a tumble."" , "Topple" , "Tip" , "Come a cropper" , "destabilise" .)