18d. Something sparkling cook gently keeps hot (7) I have S?I?M?R Could it be SWIMMER and if so, why?
23a. Large number move aimlessly round island (7) I have M?L?I?N Could it be MILLION and again, why?
20d. Calamitous sport with oval ball in America takes over.(7) I have R?I?O?S Is it ruinous and why?