Pigeon's murmur (3)
I believe the answer is:
coo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pigeon's murmur</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for coo that I've seen before include "Breathe" , "Sound coming from dovecote" , "Pigeon's sound" , "Sound made by doves" , "Murmur lovingly" .)