The cloud computing paradigm provides remote computing resources to the cloud service consumers and businesses. When combined with Internet of Things (IoT), both technologies open up a wide range of new possibilities for more agile and flexible applications. However, guaranteed quality of service is essential in provisioning of cloud services, which makes Service Level Agreements (SLAs) a focal point in the cloud computing and IoT ecosystem. The SLA definition and modeling phase is crucial in establishing SLAs between service providers and consumers. This paper identifies that the research on definition and modeling of SLAs for cloud services in IoT is widely dispersed and there is a lack of a systematic and comprehensive literature review. Thus, in this paper we build on top of a previously conducted systematic mapping study on management of SLAs for cloud computing and IoT to perform a comprehensive systematic review and discuss sub-categorization of the definition and modeling aspects of SLAs for cloud services in IoT. Furthermore we analyze the extracted relevant literature, present commonalities in the studies, identify gaps and discuss opportunities for further research in the area.