I have completed this puzzle but don´t understand the word play for 9 across: Person marching cut short active duty with queen. (7) The answer is "Parader". The wordplay also yields an extra letter, which in this clue is an ´e´. An explanation would be welcome
I think the definition is "Person marching", a parader parades,
cut short active duty, being on parade also means being on duty, without the E (cut short)
and the Queen bit is er, Elizabeth regina
R
19a was a bit sloppy really, as it works perfectly well without the extra letter. However I think the setter intended 'short active duty' to be AD and 'cut' to be PARE (with the 'E' additionally superfluous), rather than 'cut short' to be PAR(E). Pity the editor didn't spot that one !