Favourite remedy (7)
I believe the answer is:
nostrum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">favourite remedy</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nostrum that I've seen before include "Hypothetical remedy for all ills" , "Simple, remedy" , "secret potion" , "Some think it helps" , "Ineffective medical preparation" .)