Is it ensure, insure, or assure?
"to walk with a shuffling gait, walk awkwardly and unsteadily," 1680s, from an adjective meaning "ungainly, awkward" (c.1600), from shamble (n.) "table, bench" (see shambles), perhaps on the notion of the splayed legs of bench, or the way a worker sits astride it. Cf. French bancal "bow-legged, wobbly" (of furniture), properly "bench-legged," from banc "bench." The noun meaning "a shambling gait" is from 1828. Related: Shambled; shambling.