Ranting (6)
I believe the answer is:
raving
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ranting</span>' is the definition.<br/ ><span class="explanation-format__explanation">('rave' can be a synonym of 'rant')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for raving that I've seen before include "Wildly incoherent" , "Mad" , "Declaiming wildly" .)