A spell of unrestrained activity (5)
I believe the answer is:
spree
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a spell of unrestrained activity</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 spree that I've seen before include "booze-up?" , "Overindulgent bout" , "Self-indulgent bout" , "night on the razzle?" , "orgy" .)