Mishandle, as a grounder (4)
I believe the answer is:
boot
'mishandle as a grounder' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for boot that I've seen before include "Hard kick; part of car" , "Sack" , "Dismiss" , "Sturdy shoe; start (a computer)" , "Hard kick (colloq.)" .)