Drink before bedtime (8)

I believe the answer is:
nightcap
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">drink before bedtime</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nightcap that I've seen before include "what last drink might be" , "Last drink before bed" , "Last drink of the day?" , "A drink before bed, wearing nocturnal headgear" , "Alcoholic drink taken at bedtime" .)