Stuck on that top left corner .....
[25 15 refers to clues for Gold Medallist]
1A : 25 15 arm Charles's girlfriend (7) : G?N????
11A : 25 15 sulks around Her Majesty (6) : P?T???
3D : East African reran tie in dispute (8) : ??I???A?
4D : Den left with a strain (4) ??I?