A noun for “hasp, clasp” in The Etymologies of the 1930s derived from primitive ᴹ✶takmā “thing for fixing” under the root ᴹ√TAK “fix, make fast” (Ety/TAK). It is an example of how primitive ✶km developed into ngw in Quenya of the 1930s through 1950s.

Neo-Quenya: Sometime in the late 1950s or early 1960s, Tolkien revised his notion of the phonetic developments for ancient stop-nasal combinations, so that ✶km became qu (PE19/85). However, I choose to ignore this particular revision to Quenya phonology, and as such I would retain tangwa “hasp, clasp” for purposes of Neo-Quenya. I would use tangwa for a “clasp” in clothing over the word tancal(a), whose use I limit to decorative brooches. I would also use tangwa for movable fasteners in general (e.g. hasps to hold windows closed), not just in clothing.