In trouble, a king's miserable (5)
I believe the answer is:
bleak
'miserable' is the definition.
(bleak can mean miserable or unfortunate)
'in trouble a king's' is the wordplay.
'in' indicates the answer is hidden within the clue.
'BLEAK' is hidden within 'trouble a kings'.
(Other definitions for bleak that I've seen before include "Austere" , "Book by Dickens" , "Desolate, hopoeless" , "Unpleasantly cold" , "Cold and raw" .)