ensurer

noun
en·​sur·​er | \ -u̇rə(r)\
plural ensurers

Definition of ensurer

: something or someone that makes something sure or certain : one that ensures something an ensurer of success The birthstone for December is turquoise, which has long been regarded as a protective stone, a bringer of good fortune and ensurer of good health.News-Sun (Sebring, Florida), 8 Dec. 2013