Across:
  1,4. see 31
  10. My amusing dancing in competition venue (9)
  11. Give up second spot in each of my big league play ideas (5)
  12. Jogs until turnaround done with; goes beserk trying to get to the front (8)
  13. Grim reaper's lacking energy, looking more gaunt (6)
  15. When it's back it's a bad one (4)
  17. One of the 2: try to get higher value plot cultivated (4 5)
  20. Mortar hit castle - there will be a lot of running involved (9)
  21. Cannon fodder needed for many 2 (4)
  24. Firm action (6)
  25. Return of mail is arbitrary in the capital (8)
  28. Dog who might go to 2 (5)
  29. Save other mongrel (loses his cool) (9)
  30. Getting 13 to lose a pound and gain a wife, but against the tide this can be futile (8)
  31,1ac,4. Motto of 2 (English) relatives (6, 6, 8)
Down:
   1. 17 without props? (4 4)
   2,16,6. MMXVI event (5 2 3 4 8)
   3. Easy to work with? Morning has to be gone to make it possible (6)
   5. Running result put out comeback (4)
   6. see 2
   7. Fighter lost daughter in large lurid party (9)
   8. Some go to 2 amendments (6)
   9. Spits song out, as needed with "Crossroads" (9)
  14. In crude scar, testament of radical thinker (9)
  16. see 2
  18. Inner group elects crazy Trump to go around as their pick  (8)
  19. Silencer deployed with one-for-one replacement - it helps in minimising evidence (8)
  22. 2 host dances with booming bass around 27 (6)
  23. Getting hysterical at MASH - it can leave you breathless! (6)
  26. Competed in 1 down, perhaps - it's time after every fourth year (5)
  27. Grieve at report early in the day (4)