Dread keeping a king tossing and turning? (5)
I believe the answer is:
awake
'tossing and turning?' is the definition.
(I've seen this before)
'dread keeping a king' is the wordplay.
'dread' becomes 'awe' (awe can mean a feeling of dread).
'keeping' is an insertion indicator (some letters kept inside).
'king' becomes 'k' (abbreviation for king in chess).
'a'+'k'='ak'
'awe' placed around 'ak' is 'AWAKE'.
(Other definitions for awake that I've seen before include "No longer in the land of Nod" , "Not asleep" , "Make active again" , "On the ball?" , "Rouse; vigilant" .)