15a, To do with a couple of intellectuals being undecided (2,3,5) O? / T?O / ?????
20a, Colourful plot for The Good Life (3,2,5) ??? / ?? / R?S?S
23a, Sensible allowance, nearly everything! (8) R???O???
26a,Signalling when bishop ousts rook in calculation (9) B???O????