Final answer:
The structure of the nephron not working properly in glucosuria is the Proximal convoluted tubule.
Step-by-step explanation:
If there is glucosuria (glucose in the urine), it indicates that the structure of the nephron not working properly is the Proximal convoluted tubule. This is because the proximal convoluted tubule is responsible for reabsorbing glucose from the filtrate back into the bloodstream. If it is not functioning properly, glucose will not be reabsorbed effectively, resulting in glucose being excreted in the urine.