OK friends, you've given me lots of help with this but I'm still stuck on
5A - US writer accpmpanying president (6) I have ?A?O??
8D - sets aside organ as belonging to evangelist (8) I have ??R?A?K? - do I see Mark in there somewhere ?.
Sorry to be so dim - too much pre-Christmas jollity perhaps !
I hope all of you doing TLS crosswords have a Merry Christmas and a Happy New Year !