Very grateful for all help with these clues please.
11ac: “Soothing words remain in the memory? On the contrary (7).”
17dn: “Motorists commandeering stern of cruise ship: that we’ve never understood! (6,1).”
18dn: “Treat with powerful agent organised in European zoos (7).”
20dn: “A story, and not one to pass on legally (7).”
22dn: “Commentator’s not in time for West Ham’s match (5).”