Balderdash, nonsense (6)
I believe the answer is:
piffle
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">balderdash</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that balderdash can be written as piffle)</span><br/ ><br/ >'<span class="explanation-format__original">nonsense</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that nonsense can be written as piffle)</span><br/ ><br/ ></span>
(Other definitions for piffle that I've seen before include "Rubbish, nonsense" , "rot" , "Cock" , "Hogwash" , "Trivial nonsense" .)