Clumsy is probably connected with older clumse, numb from cold. It came to describe movement without dexterity, and could also describe something made in an awkward, unwieldy way.
The precise ancestry is qualified as probable. The last two meanings coexist; the trail uses their contexts rather than claiming exact dates for each extension.
Sources
- Merriam-Webster: clumsy
The probable source clumse means numb from cold; the modern senses include unskilled movement and awkward construction.
- Etymonline: clumsy
The entry connects the cold-numb family with later awkward movement and unwieldy objects.