entail v.

word-forming element meaning "in; into," from French and Old French en-, from Latin in- "in, into" (from PIE root *en "in"). Typically assimilated before -p-, -b-, -m-, -l-, and -r-. Latin in- became en- in French, Spanish, Portuguese, but remained in- in Italian.

Also used with native and imported elements to form verbs from nouns and adjectives, with a sense "put in or on" (encircle), also "cause to be, make into" (endear), and used as an intensive (enclose). Spelling variants in French that were brought over into Middle English account for parallels such as ensure/insure, and most en- words in English had at one time or another a variant in in-, and vice versa.

c. 1300, from Anglo-French tailour, Old French tailleor "tailor," also "stone-mason" (13c., Modern French tailleur), literally "a cutter," from tailler "to cut," from Late Latin or old Medieval Latin taliare "to split" (compare Medieval Latin taliator vestium "a cutter of clothes"), from Latin talea "a slender stick, rod, staff; a cutting, twig."

Although historically the tailor is the cutter, in the trade the 'tailor' is the man who sews or makes up what the 'cutter' has shaped. [OED]

The post-Latin sense development would be "piece of a plant cut for grafting," hence a verb, "cut a shoot," then, generally, "to cut." Possible cognates include Sanskrit talah "wine palm," Old Lithuanian talokas "a young girl," Greek talis "a marriageable girl" (for sense, compare slip of a girl, twiggy), Etruscan Tholna, name of the goddess of youth.

Kent. ... You cowardly rascal, nature disclaims in thee; a tailor made thee.

Corn. Thou art a strange fellow: a tailor make a man?

Kent. Ay, a tailor, sir: a stone cutter, or a painter, could not have made him so ill, though they had been but two hours at the trade.

["King Lear"]

One who makes outer garments to order, as opposed to a clothier, who makes them for sale ready-made. Tailor-made first recorded 1832 (in a figurative sense); literal sense was "heavy and plain, with attention to exact fit and with little ornamentation," as of women's garments made by a tailor rather than a dress-maker.