Split stick (6)
I believe the answer is:
cleave
This clue is a double definition.
'split' is the first definition.
(I know that split can be written as cleave)
'stick' is the second definition.
(cleave can mean to stick to something)
(Other definitions for cleave that I've seen before include "Split apart - stick together" , "remain attached" , "Part" , "Adhere or split apart" , "Divide by chopping, or cling" .)