Is it ensure, insure, or assure?
c.1300, from Anglo-French approcher, Old French aprochier "approach, come closer" (12c., Modern French approcher), from Late Latin appropiare "go nearer to," from Latin ad- "to" (see ad-) + Late Latin propiare "come nearer," comparative of Latin prope "near" (see propinquity). Replaced Old English neahlæcan.
mid-15c., from approach (v.). Figurative sense of "means of handling a problem, etc." is first attested 1905.