A new framework for DEM modelling of deformable and breakable particles is presented. In our approach, real-life particles are modelled as agglomerates (or clusters) of many DEM particles forming spherical clumps and interacting via a linear elasto-plastic force. Such interaction provides a finite equilibrium overlap, resulting in mechanically stable clusters after agglomeration. Since inter-particles bonds are elastic, clusters can be used to model particles or structures that can deform elastically, plastically or break. Different clusters can bond as well, providing the basis for modelling complex particle agglomeration. The framework is described, and key structural properties of clusters are defined and analytically related to DEM components packing and their material properties. These relations are numerically validated showing a very good agreement, enabling clusters to be designed with a precise structure. Applications of this model range from particle deformation and breakage to porous structures, from soil mechanics to die compaction and tableting. (C) 2020 Published by Elsevier B.V.