  We estimate the slope of the topological susceptibility in the three flavour
Nambu-Jona-Lasinio model with the 't Hooft interaction. The results are
consistent with the evaluation from the QCD sum rule in favour of the full
topological susceptibility. We apply it to the Shore-Veneziano formula to find
that it shows satisfactory agreement with the anomalous suppression of the
flavour-singlet axial charge. The behaviour at finite temperature is also
discussed.
