Stuck on a few this week, any help much appreciated.
8d) Runner maybe leads in international event, getting cap (6) - E - - - -.
12a) Spent penny once on article from Germany (4,2) - O - E, - -.
15a) With a word of farewell one's packed case (6) - A - I - -.
20a) Ruler departs from African country, replaced by military officer (6) S - L - A -. Sultan I think, but don't see the wordplay