Kind of rock or jazz (4)
I believe the answer is:
acid
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">kind of rock or jazz</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 acid that I've seen before include "Polluted precipitation" , "Sarcastic (could be sulphuric?)" , "- - -drop, sweet" , "Chemical compound" , "Sour (substance)" .)