The 5th Generation (5G) of mobile networks brings the concept of openness to vertical industries, by enabling new levels of programmability in the network core and edge domains. Openness is enabled through APIs and it creates the field for developing 5G-enabled vertical applications, i.e., applications that can interact with the underlay network. In this context, a programmability framework is envisaged, with major objective to support the development of 5G-enabled vertical applications, as well as, their testing, prior interacting with commercial networks. Implementation directions for the proposed framework are also provided, leading to a bunch of development and research-oriented takeaways.