Indulge Prince and Queen (6)
I believe the answer is:
pander
'indulge' is the definition.
(thesaurus)
'prince and queen' is the wordplay.
'prince' becomes 'p'.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'p'+'and'+'er'='PANDER'
(Other definitions for pander that I've seen before include "Cater to lowest tastes" , "Gratify weakness like a pimp" , "Satisfier of someone's baser wishes" , "Indulge base desires" , "Cater rto debased tastes" .)