Sentence:  She had a <WSD>receipt</WSD> to make white hair black. 
Meaning of the word marked with <WSD> tags:  <ref>[http://www.worldwidewords.org/qa/qa-rec1.htm receipt versus recipe], World Wide Words</ref><ref>[http://www.grammarphobia.com/blog/2012/11/receipt-recipe.html Grammarphobia]</ref> A recipe, instructions, prescription.