Sleeper's vision (5)
I believe the answer is:
dream
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sleeper's vision</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 dream that I've seen before include "Sleeper's vision" , "Cherished hope; reverie" , "Nocturnal vision" , "Switch off" , "It's experienced during sleep" .)