tare (tɛə)
n
1. (Commerce) the weight of the wrapping or container in which goods are packed
2. (Commerce) a deduction from gross weight to compensate for this
3. (Commerce) the weight of a vehicle without its cargo, passengers, etc
4. (Commerce) an empty container used as a counterbalance in determining net weight
Thank you for your replies. I think it's a bit of a strange clue, but will go with it. I would have thought instead of 'container' a better word to use would be 'weight', but that's just me.