n. 25B6; noun (informal)
it's a cinch : EASY TASK, child's play, five-finger exercise, gift, walkover; informal doddle, piece of cake, picnic, breeze, kids' stuff, cakewalk, pushover; Brit. informal doss; N. Amer. informal duck soup, snap; Austral./NZ informal bludge, snack; dated snip.
he was a cinch to take a prize : CERTAINTY, sure thing; Brit. informal (dead) cert.
challenge.