LEFTFIELD

LIPSCHITZGerman mathematician’s slip up with constant affected variable AUDIOBOOKNovel, we hear, about university detective and bespectacled bachelor – not bad! SAFEHAVENSanctuary BIRDWATCHWhat some Audubon Society members do with binoculars ... or a hint to 16- and 19-Across? RATIONALEProportion and flair backing up the basis of one's argument MAINPOINTBottom LINE of a speech CONVINCEDAssured HOTMINUTEPretty long time, in an idiom NOCTURNESNight airs destabilised vessels, we gather SHEETCAKERectangular birthday dessert JOINHANDSWedding officiant's directive ... or what both halves of 17-, 25-, 35- and 50-Across do? SLOWLORISWill Ross love aroused primate? TRUNCHEONStaff mid-morning meal starting late unfortunately, one behind time