I've done better than I expected when I fist looked at it, but I'm having sever difficulties in the bottom right (as well as being stuck on two in the top left).
38D - Orchestra left squeezed by narrow beams used I power cuts? (10)
Assuming this was an anagram of ORCHESTRAL I formed TROCHLEARS.
However this apparently isn't congruent with
55A - Appalling George I screwed my people (9)
the answer to which appears to be EGREGIOUS
None of these helps at all with :
57A - Dance tune in wild abandon (11)
??S???S?N?? (possibly)
While I'm at it what on earth is :
13A - Large body accepting northern policy's strength, stereotypically (9)
M?N?I???S