I think these are correct but some of the parsing eludes me...
9a. North African porter, perhaps, half heartedly doubling up (6) - BERBER (North African) It looks like 'Porter' = Bearer, minus the A, but I can't see where the B comes from.
15a. Further proof in speech by Conservative, or mug! (13) - CORROBORATION (Further proof) This looks like a homophone (in speech), of C(onservative) + OR + ROBOR (Mug), but that leaves ATION unparsed.
31a. Round that's passed through a rectangular slot? (8) - CIRCULAR (Round)
49a. An animal in the desert dropping a couple off it's back, seeing stars! (9) - ANDROMEDA (Stars)
34d. Going over without soldiers at the front leads to surrender (12) - CAPITULATION (Surrender)