We present the first cosmological measurement derived from a galaxy density field subject to a ‘ clipping ’ transformation .
By enforcing an upper bound on the galaxy number density field in the Galaxy and Mass Assembly survey ( GAMA ) , contributions from the nonlinear processes of virialisation and galaxy bias are greatly reduced .
This leads to a galaxy power spectrum which is easier to model , without calibration from numerical simulations .

We develop a theoretical model for the power spectrum of a clipped field in redshift space , which is exact for the case of anisotropic Gaussian fields .
Clipping is found to extend the applicability of the conventional Kaiser prescription by more than a factor of three in wavenumber , or a factor of thirty in terms of the number of Fourier modes .
By modelling the galaxy power spectrum on scales k < 0.3 hMpc ^ { -1 } and density fluctuations \delta _ { g } < 4 we measure the normalised growth rate f \sigma _ { 8 } ( z = { 0.18 } ) = 0.29 \pm { 0.10 } .