Allowance made for the weight of the container in which goods are packed (4)
I believe the answer is:
tare
'allowance made for the weight of the container in which goods are packed' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for tare that I've seen before include "Allowance made for the weight of the container in which goods are packed" , "Weight of container makes a vetch" , "Weight of unloaded vehicle" , "Allowance for package weight; vetch" , "Weedy annual grass, often occurs in grainfields" .)