Entry of defective product

In cost accounting provision for defective goods is already created. That can be shown in the liabilities. Finally it is written off to trading account. 

Normal spoilage 5% of input
Total spoiled units 550 units
Total Cost `10,000
Sale value of spoilage `0.50 per unit
Standard output Input less 5% of Spoilage
4,750 units
Cost of abnormal spoilage
4 750

=10 000 -250 x .5 x300/4750

= `623.68
Net cost of abnormal spoilage `623.68 – (300 x 0.50) = `473.68

Now the manufactur

ing manager can decide it to be like this

Purchases 4750

To payables a/c 4750

To Provision a/c 250

Then create a provision for 5%. When there is no defective goods

By Provision 250

By Payables 4750

To Bank a/c 5000

If there is a defect, and cannot be returned, write off the loss to profit and loss 

By Payables 4750

By provision loss 250

To bank 5000

By Provision liability 250

To Inventory 250

forgot to mention, 5000 units. I am feeling sleepy

Provisions is a different standard. Provision is usually created on accruals like receivables, warranties. Defective product provisioning will fall under capital provisioning like restructuring, dismantling Etc cause it is related to stock rather than purchases or payments.