Observer on throne with King and former Queen (8)
I believe the answer is:
onlooker
'observer' is the definition.
(I know that onlooker is a type of looker)
'on throne with king and former queen' is the wordplay.
'throne' becomes 'loo' (both can mean a toilet).
'with' means one lot of letters go next to another.
'king' becomes 'K' (abbreviation for king in chess).
'and' says to put letters next to each other.
'former queen' becomes 'ER' (Elizabeth Regina, ie Queen Elizabeth).
'on'+'loo'+'k'+'er'='ONLOOKER'
(Other definitions for onlooker that I've seen before include "Bystander" , "Spectator" , "One observes" , "Non-participant" , "Witness" .)