As usual, having spent hours on this over the weekend I'm stuck on the last few.
2d. Wish to emulate emissary who loses nothing (4)
-N--
13d. Opera opening coming up - feel sick, upset, cold in here at the Palais Garnier (1,9)
I/ - A---A---
4d. One leaving board having little time to entertain (6)
-I-E-T
21a. Too dicey suppressing describing poetry? (4)
-D--
Any help is gratefully received!