cinch

Short definition from Wiktionary

Noun

1. 1
   A simple saddle girth used in Mexico.
2. 2
   Something that is very easy to do.
3. 3
   Something that is obvious or certain to occur; a sure thing.
4. 4
   A firm hold.
5. 5
   A variety of auction pitch in which a draw to improve the hand is added, and the five of trumps (called "right Pedro") and the five of the same colour (called "left Pedro", and ranking between the five and the four of trumps) are each worth five. Fifty-one points make a game.
6. 6
   An RCA connector.

Verb

1. 1
   To bring to certain conclusion.
2. 2
   To tighten down.
3. 3
   In the game of cinch, to protect (a trick) by playing a higher trump than the five.