Patent medicine (7)
I believe the answer is:
nostrum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">patent medicine</span>' is the definition.<br/ ><span class="explanation-format__explanation">(nostrum is a kind of patent medicine)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nostrum that I've seen before include "secret potion" , "Quack cure" , "Supposed remedy" , "Quack remedy or pet scheme" , "Phoney panacea" .)