Help needed, please, with a couple of final answers. 21A One lot for many in cabbagetown - bog's back to front (8, two words) should be SLUM something and I have ?SU? for second word if 5D is tigress. Have I made an error somewhere? I think 20D must be insecta but cannot see the word play. Part of top class? Metamophoses we commonly suffer (7)
Any help gratefully received.