Cock's crest (4)
I believe the answer is:
comb
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cock's crest</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for comb that I've seen before include "Crest on the head of some birds" , "Used to tidy hair" , "Toothed grooming implement" , "Implement with teeth" , "Fastening spikes" .)