Can a clay brick waste in a soil be a source of minerals for plants?
In general clay is not a good source of nutrients. Clay is a class of hydrated alumina-silicates containing small amounts of metals. The alumina and silica are not plant nutrients, but some of the metals can be, in particular: potassium, magnesium, calcium, and iron.

Of these, only potassium is needed in large amounts by plants, and conversely, is fairly uncommon in clays. Calcium and iron are much more common, but are needed by plants in very small quantities.

For any mineral nutrient in any case I can think of, other sources would be better than clay.

Therefore, in the specific case where there was a mineral deficiency in the soil, and you didn't have another option available, clay could provide that nutrient.

However, clay can help plants in another manner. This article describes the ability of clay soil to attract and hold positive ions (metals that can be absorbed by plants are positive ions) due to the high surface area and negative surface charge of the clay particles. Since leaching can be a problem in nutrient-poor soils, having a soil component that "holds on" to those nutrients can be helpful.

Whether or not brick dust would be helpful to plant growth would depend on the specific case, in particular:


The type of plant(s)
The composition of the rest of the soil
The type of clay used to make the brick
The climate conditions (amount of rainfall, etc.)