Cut short weed (4)
I believe the answer is:
dock
I believe this clue is a double definition.
'cut short' is the first definition.
(as in docking a dog's tail)
'weed' is the second definition.
(type of weed)
(Other definitions for dock that I've seen before include "Stop (from pay); sting-soothing plant" , "Curtail - wharf" , "Court enclosure; plant" , "Where the accused is placed in court" , "Type of broad-leaved weed" .)