Nouns

(n)cinch, breeze, picnic, snap, duck soup, child's play, pushover, walkover, piece of cakeany undertaking that is easy to do“marketing this product will be no picnic”
(n)cinch, girthstable gear consisting of a band around a horse's belly that holds the saddle in place
(n)cincha form of all fours in which the players bid for the privilege of naming trumps

Verbs

(v)cinch, girthtie a cinch around“cinch horses”
(v)cinchmake sure of
(v)cinchget a grip on; get mastery of