Adjective used to describe something that is either (a) a
substitution that
doesn't quite fit the
genre or bill (b) something that is almost but not quite what it
pretends to be.
From an old Australian TV ad. When you haven't quite got what you wanted or when you've got a second rate version.
Examples: Tori Spelling is a clayton's actress. Toowoomba is a clayton's city. American beer is clayton's alcohol.