He entertains the Queen in this place (4)
I believe the answer is:
here
'in this place' is the definition.
(synonyms)
'he entertains the queen' is the wordplay.
'entertains' indicates putting letters inside.
'the queen' becomes 'ER' (Elizabeth Regina).
'he' going around 'er' is 'HERE'.
(Other definitions for here that I've seen before include "Present; I say!" , "In this place - present" , "To hand" , "final clue?" , ""___ be dragons" (old map inscription?)" .)