Very cold — incisive (6)
I believe the answer is:
biting
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">very cold</span>' is the first definition.<br/ ><br/ >'<span class="explanation-format__original">incisive</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for biting that I've seen before include "(Of wit) harsh, cruel" , "Mordant" , "Acerbic" , "Caustic or cutting - like teeth?" , "Sarcastic; very cold" .)