Need help with the last three - 13a Tree old as the Ark! (6) G-P-E- and 18a Expert on board (7) E-I-U-- and 17d The French take charge in injury (6) ---I-N
Really struggling with the last two. Hope my other answers are right.
21a Artist when old retires South (5) -E-A- and 16d Intriguing bunch of politicians (5) -A-A-...