clarifier

noun4

1. •
   One who, or that which, clarifies.

   • It is as a pioneer and “land clearer” that we know Martin-Löf – one of the principal clarifiers of the syntax and semantics of constructive mathematics. — 2012
2. •
   A speech act intended to clarify or correct one's own prior utterance.
3. •
   An additional card used to enhance or explain the primary cards in a spread.

   • […] if any card in the spread puzzles you, you can pull another card from the deck as a clarifier. — 2004
4. •
   A vessel in which the process of clarification is conducted.