The phrase "clever gimmick" refers to a smart or creative trick or strategy used to get attention or achieve a goal. It's usually something unique or unexpected that is meant to make people interested or impressed. Full definition
Which ones deliver on their claims and which products are just clever gimmicks, or fleeting trends? (drwhitneybowe.com)
The reviews have been mostly enthusiastic as well, largely complimenting how the film manages to work mostly as a whole in spite of its distractingly clever gimmick. (moviemezzanine.com)
Lost in Shadow had a very clever gimmick; your avatar is a disembodied shadow that can only travel along the shadows of other objects. (lifewire.com)