Well, I've managed most of it, but I have several annoying and scattered gaps.
Assistance with the following may improve my mood :
15A - Abandon party, withdrawing permanently (3-4)
???-?O?D
12D
It follows increase in fare (4)
S?U?
30D - Holds small book up containing Listener and unfinished Jumbo (4,4)
B?A? ??G?
42D - Russian, possibly very slow in retreat (8)
??A?I??? (VLADIMIR?)
&
54A - Coming to like people featured in a comic (7)
A?????G
I just hope everybody hasn't gone to bed early!