Beloved embracing king with the lights out (8)
I believe the answer is:
darkling
'with the lights out' is the definition.
(I've seen this before)
'beloved embracing king' is the wordplay.
'beloved' becomes 'darling' ('darling' can be a synonym of 'beloved').
'embracing' indicates putting letters inside.
'king' becomes 'k'.
'darling' enclosing 'k' is 'DARKLING'.
(Other definitions for darkling that I've seen before include "night of poetry" , "with the lights out" .)