Cat's noise (4)
I believe the answer is:
purr
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cat's noise</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 purr that I've seen before include "Sound of a contented feline" , "Cat's noise" , "Show pleasure" , "Make low, contented sound" , "Satisfaction from queen" .)