clarifier

noun

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.”

2. A speech act intended to clarify or correct one's own prior utterance.
3. A vessel in which the process of clarification is conducted.

   “the purer the sugar, when placed in the clarifier, the less lime water or blood, or temper of any kind — the less time in clarifying — and the more active vigilance at the clarifier — and the more activity also in transferring the liquor from the evaporator into the cooler will be requisite.”

4. 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.”