IPA: //ˈklɛnzər//
KK: /ˈklɛn.zɚ/
A product used to remove dirt, grease, or stains from surfaces or skin.
She used a gentle cleanser to wash her face every morning.
Cleanser → It is formed from "clean" (from Old English *clæne*, meaning free from dirt or impurities) and "-er" (meaning a person or thing that performs an action). A cleanser is something that cleans or a person who cleans.
Think of someone or something that makes things 'free from dirt' ('clean') — that's what a cleanser does.