Singer ordered to quit (6)
I believe the answer is:
resign
'to quit' is the definition.
(I know that leave office is a is a kind of of resign)
'singer ordered' is the wordplay.
'ordered' is an anagram indicator.
'singer' anagrammed gives 'RESIGN'.
(Other definitions for resign that I've seen before include "Stand down" , "Give up one's job" , "Turn over" , "advice for the incompetent?" , "Abdicate" .)