A developmental process, independent of morphogenetic (shape) change, that is required for an osteoclast cell to attain its fully functional state. An osteoclast is a specialized phagocytic cell associated with the absorption and removal of the mineralized matrix of bone tissue, and which typically differentiates from monocytes. [ GOC:pg http://purl.obolibrary.org/obo/CL_0000092 ]