ACROSS

 1 and 12  Stories of the 5? Rather a Code of Military Justice. (8,2,3)

 5 and 19  Manned in the last part of 12. (6,8)

 10  Heavy string tying up the eggs in a city of Spain? (7)

11  Aries, possibly, on part of the paper. One goes on it when really angry. (7)

12  See 1 across

13  The means to an end, offering the next sort around a deep one, possibly. (9)

14  An important time to show up your muse? (5)

16  They reputedly hovered about God’s throne. (8)

19  See 5 across

22  A drink with a degree of what some do on the floor. (5)

24  Twisted tail, surrounded by poetry–being able to do a lot of things! (9)

26  A case that might be a berth. (5)

28  Can’t seem to walk straight, like those who add things up, according to the Brits. (7)

29  Sad meow, perhaps, in sheepish environments. (7)

30  Proving a bad sister shows the way to fight things. (6)

31  What you might do after the ride, when the sun breaks out, just to confuse you. (8)

DOWN

 1  Held fast, and with a nuisance job in it. (8)

 2  Not exactly worth what you do with a ball of it. (5)

 3  Where they sing on high, sort of. (5,4)

 4  How they call things in Chicago transport, or the things you might put on the surface. (7)

 6  Ready for 5 across, having a couple of things on your side. (5)

 7  A certain plane figure starts with
only a portion coming up, but the next sounds easy, though I end up sounding hesitant. (9)

 8  Does what one wishes, to put things in the office. (6)

 9  Nice and correct, but sounds like
one that could be a support. (6)

15  This art is confused about a certain state, which could be painful. (9)

17  Fleshy plant left at rioting UCLA with the onset of anarchy. (9)

18  Frilly stuff around a certain sea, which is fair game! (8)

20  Useless to bring it up, that is, so it’s brought up inside! (6)

21  He really went through Georgia–like a tank! (7)

23  Miss Gardner and her sailor friend, possibly–in the form of a god. (6)

 25  One swears so that a rhyme is not finished! (5)

27  Feeling great satisfaction, but one doesn’t like flesh this way. (5)