Keep quiet (4,4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">keep quiet</span>' is the definition.<br/ ><span class="explanation-format__explanation">(to pipe down is to be quiet)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for pipe down that I've seen before include "Sh!" , "Say no more!" , "Shut up!" , "Be quiet!" , "make less noise" .)
(Other definitions for lie doggo that I've seen before include "Stay motionless or hidden - as canine might?" , "Hide and keep quiet" , "Stay motionless or hidden in canine manner" , "Wait concealed" , "Remain hidden in supine and canine position (3, 5)" .)