Stuck on last four:
52D: Enthusiastic with weapon (4) ?A??
47D: One that farmer on Oz stocks? (6) ?E?I??
39A: In emergency, press three of these squares (5)
N?N?S
56A: Ask for space to keep clear for new joiner (10)
?R?D?G????
I'll probably scream when someone comes up with obvious answers, but I can't spend any more time puzzling over this!