A song for one involved in ritual banner-waving (4,9)
I believe the answer is:
rule britannia
But I can't explain it at all! Could you help me understand?
(Other definitions for rule britannia that I've seen before include "Arne patriotic song" , "Britons never slaves song" , "Patriotic British song" , "Thomas Arne's patriotic composition" , "Regular Last Night of the Proms number" .)