To climb, using both feet and hands; climb with effort or difficulty. (Dictionary.com)
To climb up, across, or into somewhere with difficulty, using the hands and the feet. (Cambridge Dictionary)
To climb awkwardly (as by scrambling) (Merriam – Webster)
If you clamber somewhere you climb there with difficulty, usually using your hands as well as your feet. (Collins Dictionary)
Clamor vs clamber.