Full stop (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">full stop</span>' is the definition.<br/ ><span class="explanation-format__explanation">(US name for a full stop)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for period that I've seen before include "Phase" , "Stretch - cycle" , "Era, epoch" , "End of story" , "Amount of time - US full stop" .)
(Other definitions for kibosh that I've seen before include "Rubbish - nonsense" , "Fatal to put this on" , "Put the ___ on - rubbish" , "Put this on something and stop it from happening" , "Terminate" .)