HIDDENSTAIRCASE

ASANENDINITSELFHow humanity exists, per Kant LOSTONESDIGNITYDidn't save face ADVENTCALENDARSTheir last windows are opened on Christmas Eve BOOGIEDOWNBRONXHip-hop's birthplace, colloquially ARMOREDDINOSAURAnkylosaurus, for one VOICECONTROLLEDSmart, in a way SEEMSREASONABLE"That's not so outrageous" COLORADOSPRINGSDesperately poor lad crossing city INCOMPLETEGRADEI may stand for it BOLTONWANDERERSEccentric wore brand stolen from football club HAVETHELASTWORDGet final say in an argument, e.g. INCIDENTALMUSICPopular tune - claim disc misrepresented original theatrical version? PUTAFACETOANAMEFinally meet in person, or how to make the starred clues match their answers LAUGHOUTOFCOURTRefuse to consider some fun, having nowhere to play tennis?