Duffy's TV commercial for Diet Coke has reportedly provoked a flurry of complaints.
The ad showed the singer coming offstage before sipping the drink and cycling through dark streets and into a supermarket, before returning to her concert to perform an encore.
The British advertising watchdog said 18 viewers questioned whether the ad condoned behaviour "prejudicial to health and safety", because Duffy wasn't wearing reflective clothing and her bike had no lights, and there were also four complaints about whether the ad was irresponsible because children might copy her behaviour.
Coca-Cola argued the ad wasn't meant to reflect reality, but rather "Duffy's fantasy, a scenario that depicted her escape from the pressures of stardom and far removed from the real world".
Nonetheless, the company said they had gone through a "vigorous" production process to ensure they met the Highway Code criteria for riding a bike on public roads.
With the regulations recommending cyclists wear reflective clothing in the dark, Coca-Cola pointed out that the star wore a black and white sparkly top that stood out, while her bicycle had lights on the front and rear in each shot.
After investigating, the advertising watchdog didn't uphold the complaints, noting the "fantasy context" and deciding that older children would understand cycling round a supermarket wasn't a realistic situation.
