Cool, man! (3)
I believe the answer is:
rad
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">cool</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">man</span>' is the second definition.<br/ ><br/ ></span>
(Other definitions for rad that I've seen before include "measure of dangerous activity" , "Unit of radiation" .)