$2$-approximate algorithm for finding a clique with minimum weight of vertices and edges

The problem on a minimal clique (with respect to the total weight of its vertices and edges) of fixed size in a complete undirected weighted graph is considered along with some of its important special cases. Approximability questions are analyzed. The weak approximability of the problem is established for the general case. A $2$-approximate effective algorithm with time complexity $O(n^2)$ is proposed for cases where vertex weights are nonnegative and edge weights either satisfy the triangle inequality or are squared pairwise distances for some system of points of a Euclidean space.