Burden or weight (4)
I believe the answer is:
load
This clue is a double definition.
'burden' is the first definition.
(I know that burden can be written as load)
'weight' is the second definition.
(I know that load is a type of weight)
(Other definitions for load that I've seen before include "Burden, onus" , "Cargo - burden" , "A heavy burden" , "Amount" , "Goods carried by a large vehicle" .)