Impede, burden (8)
I believe the answer is:
encumber
This clue is a double definition.
'impede' is the first definition.
(I've seen this before)
'burden' is the second definition.
(I've seen this before)
(Other definitions for encumber that I've seen before include "Impede, burden" , "Constrain" , "Burden with, oppress (8)" , "Restrict or impede" , "Be a burden to, place load on" .)