Taken from the brand name of popular DIY Gap Filler, Selleys, a Selley is a partner or fling that fills the gap of time between actual significant relationships.
Friend 1: "Damn Blake has gotten fat"
Friend 2: "Oh well he was just a Selleys"
Friend 1: "I'm not interested in a boyfriend, but I am in the market for some Selleys"
Friend 2: "Sounds about right, got to plug those holes"
selleys allclear is a type of glue to keep out water of cracks, windows etc, it is also used as a cheap high for kids, they squeeze the glue out of the 600ml bottle or tube and place it in a aplastic bag and then start to inhale.
selleys allclear it is like croming in a liquid form 'never eat it'