5G is the key enabler for new business and digital transformation initiatives to integrate vertical industries (e.g., automotive, energy, manufacturing, entertainment) into the network slice concept, maximizing the sharing of network resources and creating dedicated logical networks with personalized customer specific functions. In this paper we present a unique concept for the development, deployment and management of a Smart City 5G cloud native application network as a result of synergy between two 5G-PPP EU projects, namely MATILDA and SliceNet. The application development and deployment lifecycle starts with the design and composition of the application graph in MATILDA development kit, followed by on boarding of the developed application into a vertical applications orchestrator and the preparation of a "slice intent" description for the creation of an application-aware network slice. The latter is provided to the SliceNet One-Stop API to create the application-aware network slice to be deployed further over a programmable network infrastructure. The overall Smart City use case is presented, including plans for further enhancements as a collaborative activity between the two research projects. All functions and integration activities will be tested in a dedicated testbed platform.